                     The Discover Hardware Detection System

  G. Branden Robinson

  John R. Daily

   Copyright (c) 2002 Progeny Linux Systems, Inc.

   Copyright (c) 2002 Hewlett-Packard Company

   Permission is hereby granted, free of charge, to any person obtaining a
   copy of this software and associated documentation files (the "Software"),
   to deal in the Software without restriction, including without limitation
   the rights to use, copy, modify, merge, publish, distribute, sublicense,
   and/or sell copies of the Software, and to permit persons to whom the
   Software is furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.

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   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
   THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   DEALINGS IN THE SOFTWARE.

   Linux is a registered trademark of Linus Torvalds.

   $Progeny$

     ----------------------------------------------------------------------

   Table of Contents

   What Is Discover?

   I. Data Structure

                1. Overview of the Discover Data Format

                2. Master List

                3. Busclass Lists

                             3.1. The busclass_list element

                                          3.1.1. The bus attribute

                             3.2. The busclass element

                                          3.2.1. The id attribute

                                          3.2.2. The name attribute

                4. Vendor Lists

                             4.1. The vendor_list element

                                          4.1.1. The bus attribute

                             4.2. The vendor element

                                          4.2.1. The id attribute

                                          4.2.2. The name attribute

                5. Device Lists

                             5.1. The device_list element

                                          5.1.1. The bus attribute

                             5.2. The device element

                             5.3. The data element

                                          5.3.1. The class attribute

                                          5.3.2. The version attribute

                             5.4. Accessing the Device Data

   II. Recommended Data Content Conventions

                6. Data Hierarchy

                             6.1. Linux Kernel Modules

                             6.2. XFree86 X Servers

                             6.3. Locally-Defined Interfaces

                7. Why Order Matters

                8. Using Data Versioning

                             8.1. Specifying a Range

                             8.2. How the Discover Library Matches a Range

   III. Command-Line Tools

                9. discover Manual Page

                             discover -- hardware detection utility

                10. discover.conf Manual Page

                             discover.conf -- configuration file format for
                             discover(1)

                11. discover-modprobe Manual Page

                             discover-modprobe -- kernel module loading using
                             discover(1)

                12. discover-modprobe.conf Manual Page

                             discover-modprobe.conf -- configuration file for
                             discover-modprobe(5)

   IV. Library

                13. The Discover Library

                             13.1. Library Design Principles

                             13.2. Discover Data Sources

                             13.3. The Bus Map

                             13.4. Scanning the System

                             13.5. Using discover_device_t Structures

                14. System Dependencies

                             14.1. API

   A. Discover API Reference

   B. Discover DTD

   C. Discover Configuration File DTD

   D. Licensing Issue on the Linux Sysdeps

   List of Figures

   6-1. Linux interface

   6-2. XFree86 interface

   List of Examples

   3-1. The busclass_list element

   4-1. The vendor_list element

   5-1. Sample device data

   6-1. Defining an interface

   6-2. Using the linux interface

   6-3. Using the xfree86 interface

   7-1. Matching device elements

   8-1. Using the version attribute of the data element

   9-1. Scan the local buses

   9-2. View PCI video cards

   9-3. Query for the driver module for XFree86 server version 4.2.0

   9-4. Get model and vendor information by type

   10-1. Establishing default buses to scan

   10-2. A more complex example

   14-1. Linux PCI sysdep code

     ----------------------------------------------------------------------

                               What Is Discover?

   Discover is a tool that reports information about a system's hardware. It
   uses operating system-dependent modules (selected at build time) to detect
   what hardware is actually on the system and provides system-independent
   interfaces for querying XML data sources about this hardware. These data
   sources contain specific information required to enable support for
   various devices via defined software interfaces. The tool can be accessed
   by linking to the Discover library or by calling discover (which itself
   links to the Discover library) and parsing its output. In the future,
   other interfaces (for example, modules for interpreted languages such as
   Perl and Python) may be included.

   Why use Discover? There are at least a few reasons:

     * Flexibility. Discover is designed from the ground up to be flexible.
       It is portable to a variety of operating environments, and its modular
       design supports the addition of arbitrary methods for querying the
       host operating system (OS) about installed devices. Discover is also
       designed to be flexible in terms of the types of data that can be
       retrieved. Discover does not tie the user to retrieving only one type
       of information, such as the name of the Linux kernel module that
       should be loaded to support a given device. Instead, Discover supports
       the association of arbitrary data with hardware devices, typically
       through specification of an interface to the hardware in question,
       such as a Linux kernel module or an XFree86 server driver module.

     * Updatability. Many hardware-autodetection programs suffer from an
       inherent limitation in that they are restricted to reading hardware
       lists or databases that are stored on the local filesystem. This is
       not an efficient approach in the fast-moving world of consumer
       computer hardware, with new devices constantly being introduced. A
       couple of months after the latest version of your OS of choice is
       released, it may fail to recognize that the latest revision of, for
       instance, a video chipset is compatible with an older one, and can use
       the same software interfaces. Discover overcomes this problem by
       supporting the retrieval of hardware information via HTTP[1] ("over
       the web"). When HTTP access is impossible, Discover falls back to
       locally stored hardware lists.

     * Portability. On top of its flexibility in terms of system interfaces
       to hardware, Discover has been written to be broadly portable to all
       of today's popular POSIX-compliant systems. Discover is not a
       Linux-only solution. Discover is intended to provide operating system
       vendors, computer manufacturers, and third-party vendors of software
       and peripherals with a powerful tool for describing the hardware they
       support to the interfaces they care about. Because Discover's data
       sources can be anywhere on the Internet, the OS vendor need not be the
       sole provider of hardware catalogs.

     * Usability. Discover is not an in-house tool designed to solve a narrow
       class of problems. Discover is designed to be easy to use from the
       perspectives of the individual system administrator, the applications
       programmer, and the hardware manufacturer or support staff. Discover's
       XML database structure, its command-line tools, and its library API
       are well documented and support extensions to meet diverse demands.

     * Freely licensed. Discover has a copyright license that is highly
       adaptable to the needs of the varied audiences to which Discover is
       targeted. Under the so-called "UCB/BSD" or "MIT/X Consortium" terms,
       after the names of American universities and some very well known
       software projects that used these terms, anyone is free to copy,
       modify, and distribute the software, and to extend (or not) these same
       freedoms to those who receive the software. Progeny would like to see
       Discover adopted by a wide variety of existing software products, such
       the various GNU/Linux distributions; the FreeBSD, NetBSD, and OpenBSD
       projects; the GNU Project of the Free Software Foundation; the XFree86
       Project; system integrators; and the designers and manufacturers of
       computer hardware. We believe that Discover's design empowers those
       with the greatest knowledge of hardware and the software interfaces to
       that hardware to express that knowledge and make it available to the
       world, thereby ameliorating an entire class of computer configuration
       problems. Progeny does not want Discover's licensing to stand in the
       way of realizing that dream, which is why we have chosen these license
       terms.

   We must take a moment to explain what Discover is not: Discover is not a
   replacement for the service - usually provided by the underlying operating
   system kernel or a user-space program that interfaces with it - of simply
   translating bus-specific vendor and model identifiers to human-readable
   names. Discover performs its own translations of this data as a
   convenience for generating human-readable reports, but it does not attempt
   to enumerate all hardware devices that exist for a particular bus
   architecture. Rather, Discover is intended only to catalog data for which
   there is some useful information to impart regarding software interfaces.
   Facilities already exist in modern operating systems for answering the
   questions "What is the name of this device?" and "Who manufactured it?"
   Discover's role is to answer questions like "What Linux kernel module do I
   need to load for this device to work?" More importantly, Discover will
   enable you to provide answers in the future to questions you don't even
   expect to ask today.

   Discover is not intended to be a comprehensive hardware-management tool.
   It is an enabling technology, designed to provide data that a tool layered
   above it can use. Two applications are provided with Discover to
   demonstrate how the library can be leveraged: the command-line utility
   discover, and a Linux kernel module loading script, discover-modprobe,
   designed to be invoked at system boot time.

   This manual is divided into four parts. First, we examine the Discover XML
   data file format, exploring the elements and attributes used to describe
   hardware and various interfaces to it. This part will enable you to read
   and understand a Discover XML file. Next, we offer some recommendations
   for writing your own Discover XML data. Knowing the syntax is valuable,
   but knowing how best to take advantage of it is even more useful. We then
   present the reference pages describing Progeny's Discover-based
   command-line tools and the configuration files used to control their
   behavior. You may want to use these references as a guide when
   implementing your own Discover-based applications. The final part
   describes the Discover library API so that you can develop your own
   solutions based on Discover. Appendices offer references to the formal
   descriptions of the Discover API and XML DTDs.

                               I. Data Structure

   Table of Contents

   1. Overview of the Discover Data Format

   2. Master List

   3. Busclass Lists

                3.1. The busclass_list element

                             3.1.1. The bus attribute

                3.2. The busclass element

                             3.2.1. The id attribute

                             3.2.2. The name attribute

   4. Vendor Lists

                4.1. The vendor_list element

                             4.1.1. The bus attribute

                4.2. The vendor element

                             4.2.1. The id attribute

                             4.2.2. The name attribute

   5. Device Lists

                5.1. The device_list element

                             5.1.1. The bus attribute

                5.2. The device element

                5.3. The data element

                             5.3.1. The class attribute

                             5.3.2. The version attribute

                5.4. Accessing the Device Data

     ----------------------------------------------------------------------

                Chapter 1. Overview of the Discover Data Format

   Most modern computer peripherals contain self-identifying information in a
   format standardized for the hardware interface (bus). This enables the OS
   on the host system to query or scan a bus and catalog the devices. In
   general, the OS stores this information in the same basic format in which
   it is returned, without translating it more times than necessary for
   device drivers to communicate with the peripheral. However, this
   information varies by bus type and is often insufficiently clear for human
   consumption. Furthermore, many operating systems do not contain a
   comprehensive database that maps each peripheral to every subsystem
   running on the OS that may want to communicate with that peripheral.
   Discover addresses these issues by providing flexible databases stored in
   XML format.

   Extensible Markup Language (XML) is a highly flexible hypertext format.
   Discover uses XML exclusively to store hardware information externally.
   Some familiarity with XML syntax is therefore assumed. For more
   information, see the W3C's XML website.

   For a formal description of Discover's XML data format, see the Discover
   Document Type Definition (DTD) document. The purpose of this document is
   to present the information in a form digestible by the novice.

   Because each hardware bus type, such as PCI or USB, communicates different
   details about the connected devices (essentially, each one solves the same
   problem in a different way), Discover has a different set of lists for
   each bus type. For each bus, up to three lists are stored: a bus class
   list maps the bus specification's notion of a device type (hereinafter
   referred to as a "device class" to reduce confusion) to Discover's device
   types, which are used for running selective queries; a vendor list
   associates bus-specific vendor identification data with natural-language
   names for hardware vendors; and a device list contains information
   specific to individual devices.

     ----------------------------------------------------------------------

                             Chapter 2. Master List

   When Discover is provided with a URL for the retrieval of hardware
   information, the data retrieved is expected to be in XML format and to
   contain further URLs for retrieval.

   The root element must be discover-data, which has no attributes, and can
   only contain location elements.

   The location element is always empty, and has three required attributes:
   bus, type, and url.

   location Attributes

   type

           This attribute can have one of these values: busclass, device, or
           vendor. See Chapter 3, Chapter 4, and Chapter 5.

   url

           This must be a valid URL containing one of the three types of data
           lists.

   bus

           This is the bus to which the URL applies. See Section 3.2.2 for a
           list of valid bus names.

     ----------------------------------------------------------------------

                           Chapter 3. Busclass Lists

   As noted in the previous chapter, a busclass list provides a mapping
   between device classes recognized by the hardware bus and the device type
   names used by Discover. Because every bus is different, sometimes there is
   no perfect, one-to-one correspondence between Discover device types and
   the device classes recognized by a particular bus. This is one reason that
   the busclass lists, like other types of Discover data lists, are
   updatable. Revisions in a bus specification may demand updates to the
   mapping.

   The device classes recognized by a bus are typically determined by the
   specification for the bus as determined by a standards committee or other
   technical body, and do not change frequently (if at all).

   Example 3-1. The busclass_list element

   <?xml version="1.0"?>                                                      
                                                                              
   <busclass_list bus="usb">                                                  
     <busclass id="0202" name="modem"/>                                       
     <busclass id="1030" name="broadband"/>                                   
     <busclass id="0101" name="printer"/>                                     
     <busclass id="ffff" name="imaging"/>                                     
     <busclass id="0206" name="network"/>                                     
     <busclass id="0300" name="humaninput"/>                                  
     <busclass id="ff00" name="video"/>                                       
     <busclass id="0000" name="unknown"/>                                     
     <busclass id="0804" name="removabledisk"/>                               
   </busclass_list>                                                           

   In the foregoing example, we can see one possible mapping of the USB bus's
   numeric device class IDs to Discover's device type names (see Section
   3.2.2). The file begins by declaring the version of the XML standard to
   which it conforms, and then presents data. The format should be fairly
   familiar to those accustomed to HTML-style structured markup languages.

   Not all of Discover's supported device types are listed in the example;
   for example, display is missing. This is not a problem, since not all
   buses are used for all hardware applications. USB 1.1 would be a poor
   choice of bus for VGA-compatible display controllers, for instance,
   because the available bandwidth on the USB 1.1 bus is insufficient to
   handle typical data loads for such devices.

   Another infelicity in the above example is the association of the ffff
   device class ID with the Discover device type imaging. In actuality, a
   device type class of ffff in the USB specification indicates a device of
   an unknown classification. In practice, most consumer-level devices with
   this device class are scanners, one of the first applications of USB
   technology in the consumer marketplace. It is possible that in certain
   deployments, the association of USB's unknown device class ID with
   Discover's imaging device type is suboptimal - another reason the busclass
   lists are not hard-coded into the library.

     ----------------------------------------------------------------------

3.1. The busclass_list element

   A busclass_list element possesses a bus attribute and contains one or more
   busclass elements.

     ----------------------------------------------------------------------

  3.1.1. The bus attribute

   The bus attribute of the busclass_list element is set to the name of the
   bus being described by the busclass list.

   The bus attribute presently supports the following values:

     * ata

     * pci

     * pcmcia

     * scsi

     * usb

   We expect to support more buses in the future; ieee1394 and sbus are
   possible candidates.

     ----------------------------------------------------------------------

3.2. The busclass element

   A busclass element possesses two attributes, id and name, and contains no
   elements.

     ----------------------------------------------------------------------

  3.2.1. The id attribute

   The id attribute is set to a bus-specific device class identifier.

     ----------------------------------------------------------------------

  3.2.2. The name attribute

   The name attribute is set to a Discover device type. Discover's device
   types are an effort to balance a few criteria:

     * Device types ("bus classes" in Discover terminology) defined by the
       PCI specification

     * Bus classes defined by the USB specification

     * Bus classes defined by the SCSI specification

     * Device types commonly conceived of by the personal computer user

   Discover's definitions of device types will not meet with universal
   agreement; as happens in most categorization problems, some decisions had
   to be made arbitrarily. Discover does not attempt to solve the general
   problem of grouping various peripherals into categories; rather, Discover
   solves the problem for itself and uses bus-specific mappings to translate
   a device's own notion of its type to Discover's device type.

     * audio

       A device capable of producing an analog or digital sound signal is an
       audio device. Typically, any device commonly referred to as a "sound
       card" is classified by Discover as an audio device.

     * bridge

       A device that provides access to devices of a different type, commonly
       on a different bus, is a bridge device. For instance, consumer PCI
       chipsets often feature a bridge to ATA (also known as IDE) devices.

     * broadband

       An interface device to a computer communications network implemented
       on top of a technology not explicitly designed for that purpose is a
       broadband device. Examples include ISDN terminal adapters as well as
       DSL and cable "modems"; analog phone-line modems are not included in
       this classification (see "modem" below).

     * display

       A device controlled by the host machine's CPU and capable of producing
       an analog or digital video signal for output purposes is a display
       device. Typically, any device commonly referred to as a "video card"
       is classified by Discover as a display device.

     * fixeddisk

       A high-speed, fixed magnetic storage device such as a hard disk drive
       is a fixeddisk device. Removable media devices such as floppy disk
       drives, CD-ROM drives, magneto-optical devices, tape drives, and
       Compact Flash card readers are not included in this classification.

     * humaninput

       A device that receives tactile input from a person for the purpose of
       directing a computer's activity is a humaninput device. Examples
       include keyboards, mice, trackballs, joysticks, gamepads, digital
       tablets manipulated with a stylus or finger, and so forth. Input
       devices that rely upon non-tactile means of determining a person's
       intent, such as speech-recognition devices or cameras, are not
       included in this classification.

     * imaging

       A device that captures still images for input purposes is an imaging
       device. Scanners and digital cameras are examples of imaging devices.
       Motion-capture devices such as television tuner cards, webcams, and
       digital video cameras are not included in this classification.

     * miscellaneous

       Any device that cannot logically be classified as another device type
       is a miscellaneous device.

     * modem

       An analog phone-line modulator/demodulator (modem) is classified by
       Discover as a modem device. No other kind of device is so classified.

     * network

       An interface device to a conventional computer data communications
       network that does not require the use of a terminal adapter is a
       network device. For example, Ethernet and Token Ring network interface
       cards are network devices. Analog phone-line modems; terminal adapters
       for technologies such as ISDN and DSL; and "cable modems" are not
       "network" devices.

     * optical

       An optical-technology storage device, often using read-only media, is
       an optical device. By far the most common examples of these devices
       are CD-ROM and DVD-ROM drives, including versions of these drives that
       can "burn" (write to) optical discs.

     * printer

       A device that renders visual output in a permanent or semi-permanent
       manner to a physical medium is a printer. Typically, any device
       colloquially referred to as a "printer" is also classified by Discover
       as a printer.

     * removabledisk

       Storage devices that feature removable media using just about any
       technology except that of magnetic tape, CD-ROM, and DVD-ROM drives
       are removabledisk devices. Examples include floppy disk drives,
       magneto-optical drives, and Compact Flash card readers.

     * tape

       A sequential-access mass storage device using magnetic tape is a tape
       device. Commonly used for archival and backup purposes, DAT drives are
       examples of tape devices.

     * video

       A device that produces a real-time digital video signal for input
       purposes is a video device. Webcams, digital video cameras, and
       television tuners are examples of video devices. Note that still
       digital cameras with "movie" capability are not considered video
       devices unless they can transmit the live video signal to the host in
       real time.

     ----------------------------------------------------------------------

                            Chapter 4. Vendor Lists

   Many buses have vendor identification numbers that are registered with
   that bus's standardization body and programmed into the devices when they
   are manufactured. These numbers generally are assigned arbitrarily, and
   typically have little meaning to the end user; therefore, most hardware
   detection tools provide a way to translate these numeric vendor IDs to
   human-readable strings. Thus, instead of knowing that your PCI or AGP
   video card was manufactured by "1002," you can determine that it was
   manufactured by "ATI Technologies, Inc."

   Example 4-1. The vendor_list element

   <?xml version="1.0"?>                                                      
                                                                              
   <vendor_list bus="pci">                                                    
     <vendor id="0675" name="Dynalink"/>                                      
     <vendor id="0e11" name="Compaq Computer Corporation"/>                   
     <vendor id="1004" name="VLSI Technology Inc"/>                           
     <vendor id="1025" name="Acer Incorporated [ALI]"/>                       
     <vendor id="102b" name="Matrox Graphics, Inc."/>                         
     <vendor id="109e" name="Brooktree Corporation"/>                         
   </vendor_list>                                                             

   The foregoing example is similar in structure to the busclass list
   example; a numeric vendor ID maps to a vendor name, which can be used by
   Discover for queries or reports generated for the user's benefit.

     ----------------------------------------------------------------------

4.1. The vendor_list element

   A vendor_list element possesses a bus attribute and contains one or more
   vendor elements.

     ----------------------------------------------------------------------

  4.1.1. The bus attribute

   The bus attribute of the vendor_list element is set to the name of the bus
   being described by the vendor list.

   The following bus attributes are supported:

     * ata

     * pci

     * pcmcia

     * scsi

     * usb

     ----------------------------------------------------------------------

4.2. The vendor element

   A vendor element possesses two attributes, id and name, and contains no
   elements.

     ----------------------------------------------------------------------

  4.2.1. The id attribute

   The id attribute is set to a bus-specific vendor identifier.

     ----------------------------------------------------------------------

  4.2.2. The name attribute

   The name attribute is set to a human-readable vendor identifier, typically
   the official name of the corporation or other business entity that
   designed or manufactured that peripheral.

     ----------------------------------------------------------------------

                            Chapter 5. Device Lists

   The device lists are the heart of Discover's functionality. They are the
   most frequently updated lists and contain the information of greatest
   value.

   Discover's device lists not only provide a way to identify individual
   peripherals by name, but also permit the specification of an arbitrary
   quantity of organized data for each device, supporting an arbitrary number
   of software interfaces.

   Note The following is a fictitious example. The information within it is   
        for illustrative purposes only. See Part II in The Discover Hardware  
        Detection System for a discussion of the "real" hardware data as      
        provided by Progeny, and for some suggested conventions on organizing 
        the data namespace.                                                   

   Example 5-1. Sample device data

<?xml version="1.0"?>                                                                    
                                                                                         
<device_list bus="pci">                                                                  
  <device busclass="1984" model="0101" model_name="Cerebral Reprogrammer" vendor="B16B"> 

        winston                                                
        base_address=0x300 manual_override=0                

        settlement                
        NSA_KEY=96b5f3e3283a62c85f6cb6f4017135c2              

  </device>                                                                              
</device_list>                                                                           

   The example above includes a device_list element containing device
   elements, and a device element that defines the device itself, but
   reserves any software- or interface-specific details to the data elements
   it contains.

   The actual data provided in the example is accessed by means of data
   paths; see Section 5.4 for further information.

     ----------------------------------------------------------------------

5.1. The device_list element

   A device_list element possesses a bus attribute and contains one or more
   device elements.

     ----------------------------------------------------------------------

  5.1.1. The bus attribute

   The bus attribute of the device_list element is set to the name of the bus
   described by the device list.

   The following bus attributes are supported:

     * ata

     * pci

     * pcmcia

     * scsi

     * usb

     ----------------------------------------------------------------------

5.2. The device element

   A device element possesses four attributes:

     * busclass

     * vendor

     * model

     * model_name

   All of these attributes must be specified for each device element. The
   busclass attribute is set to a busclass identifier, vendor to a vendor
   identifier, model to a bus-specific model identifier, and model_name to a
   human-readable vendor identifier, typically the name of the product under
   which the device reporting the model identifier is sold or otherwise
   distributed.

   A device element contains zero or more data elements.

     ----------------------------------------------------------------------

5.3. The data element

   A data element possesses a mandatory class attribute, an optional version
   attribute, and zero or more data elements.

   The ability to nest data elements inside other data elements affords
   interface designers and device driver authors the ability to specify a
   hierarchy of data, instead of being compelled to encapsulate only one
   piece of data per device for their interface.

     ----------------------------------------------------------------------

  5.3.1. The class attribute

   A class attribute is set to an arbitrary value determined by an interface
   designer. For data elements whose parent element is a device element, this
   should be the name of the interface being described, such as freebsd,
   linux, or xfree86.

   A data element whose parent element is a data element should set this
   attribute to a term reflecting the interface designer's intended data
   hierarchy. Discover does not mandate any particular hierarchy for
   interface designers.

     ----------------------------------------------------------------------

  5.3.2. The version attribute

   Data elements have an optional attribute named version. This indicates a
   version range applicable to the data contained within the element. The
   purpose of this attribute is to permit the specification of data that is
   valid only for a range of versions of the given interface. For example,
   the Linux kernel changed some of the names of its modules between the 2.2
   and 2.4 series.

   Discover's range syntax, common in mathematical writings, is expressed as
   an interval; that is, it consists of a pair of endpoints with a comma
   between them, and brackets or parentheses as qualifiers for inclusion or
   exclusion of the endpoints' exact values. For example, the version
   specification [1.0, 2.0) matches any version less than 2.0 and greater
   than or equal to 1.0. It is the responsibility of the calling environment
   to specify the version of the interface actually in use. In other words,
   the Discover library does not take it upon itself to determine the
   currently running version of the Linux kernel, XFree86 X server, CUPS
   printing daemon, and so forth.

   Due to the lack of consistent standards for version numbers (in fact, some
   version numbers aren't numbers at all), Discover requires simplifications
   for the version attribute. The versions that express the range must be in
   dotted-decimal form, such as 7.1.0. The version that is supplied to the
   Discover library as part of a query (for example, via the --data-version
   argument to discover) may or may not comply with this requirement, but
   should be expressed such that it compares in a desirable way against
   version strings that do.

   In place of the upper end of the range, inf (infinity) can be used if the
   information is still relevant and should be for forseeable versions.

     ----------------------------------------------------------------------

5.4. Accessing the Device Data

   Discover data is grouped into hierarchical data elements. This data can be
   accessed via its data path. The data path is the concatenation of the
   class attribute values of a data element and all its parents, separated by
   slash (/) characters. In the following example, quux is accessed via the
   data path "foo/bar":

     quux                                            

   In Example 5-1 above, we would determine the name of the Linux kernel
   module ("winston") for the "Cerebral Reprogrammer" device by referencing
   the data path linux/module/name; similarly, the data path
   win2k/hal_driver/flags returns NSA_KEY=96b5f3e3283a62c85f6cb6f4017135c2.

                    II. Recommended Data Content Conventions

   As discussed in the preface, Discover is not intended to be a replacement
   for system utilities such as lspci on Linux. A device element should exist
   for a piece of hardware only if there is some interface information to
   communicate about the hardware; that is, some data elements to house
   within the device element. This part of the manual contains Progeny's
   recommendations on how to organize that information for maximum utility.

   Table of Contents

   6. Data Hierarchy

                6.1. Linux Kernel Modules

                6.2. XFree86 X Servers

                6.3. Locally-Defined Interfaces

   7. Why Order Matters

   8. Using Data Versioning

                8.1. Specifying a Range

                8.2. How the Discover Library Matches a Range

     ----------------------------------------------------------------------

                           Chapter 6. Data Hierarchy

   As discussed in Section 5.4, the XML structure around the data allows for
   a hierarchical view.

   While Discover does not mandate any particular hierarchy or namespace
   organization for data elements, the XML files provided by Progeny express
   - and some applications based on Discover (such as discover-modprobe)
   expect - a certain structure for Linux kernel module and XFree86
   configuration information.

   At Progeny, we have often found it convenient to refer to a top-level data
   element's class attribute value as an "interface" (see the following
   example).

   Example 6-1. Defining an interface

   <device busclass="0300" vendor="de8d" model="90a9" model_name="Stingray">  

         XF86_SVGA                                  

       untrusted                          
                                                                       
   </device>                                                                  

   In Example 6-1, two interfaces have been defined for the "Stingray"
   device: xfree86 and openbsd.

     ----------------------------------------------------------------------

6.1. Linux Kernel Modules

   A hardware device that requires a particular Linux kernel module should
   have nested data elements to describe that module. The top-level data
   element should have a class attribute with a value of linux. Underneath
   that should be a data element with a class of module.

   Within that data element, there should be one or two more, one with a
   class of name, and an optional one with a class of options. The former has
   as content the name of the module; the latter, options to be passed to
   modprobe.

   Figure 6-1. Linux interface

   /linux                                                                     
       |                                                                      
       |-/module                                                              
             |                                                                
             |-/name                                                          
             |                                                                
             |-/options                                                       

   In Figure 6-1, each component of the tree represents a data element; the
   label is the value of its class attribute.

   If the kernel version affects the choice of module name or options, the
   top-level linux data element should have a version range attribute; see
   Section 5.3.2.

   Example 6-2. Using the linux interface

<device busclass="0204" model="1702" model_name="IS64PH ISDN Adapter" vendor="0675"> 

       hisax                                               
       io=0x300 irq=11                                  

</device>                                                                            

   See Example 8-1 for guidance on how to specify different Linux kernel
   modules for the same device, depending on the version of the Linux kernel
   in use.

     ----------------------------------------------------------------------

6.2. XFree86 X Servers

   The data hierarchy of a video card device (Discover's display type) should
   include a top-level data element with a class attribute of xfree86 (the
   interface) and likely with a version attribute as well; nested within that
   element will be a server data element containing a name data element
   identifying the name of the server executable. For XFree86 version 4.0 or
   greater, the name will always be XFree86, and the server data element will
   also contain a device data element, which contains one or more data
   elements communicating information to be stored in the XF86Config file.
   The children of the device data element are named in correspondence with
   the syntax of the XF86Config file's Device section; see the XF86Config
   manual page for further information. In particular, note that in many
   cases only a driver data element is necessary.

   Figure 6-2. XFree86 interface

   /xfree86                                                                   
       |                                                                      
       |-/server                                                              
             |                                                                
             |-/name                                                          
             |                                                                
             |-/device                                                        
                   |                                                          
                   |-/driver                                                  
                   |                                                          
                   |-/chipid                                                  
                   |                                                          
                   |-/chipset                                                 
                   |                                                          
                   |-/ramdac                                                  
                   |                                                          
                   |-/dacspeed                                                
                   |                                                          
                   |-/videoram                                                
                   |                                                          
                   |-/options                                                 
                   |                                                          
                   |-...                                                      

   Figure 6-2 illustrates the xfree86 interface. Example 6-3 shows how you
   might write xfree86 interface information for a Discover display device.

   Example 6-3. Using the xfree86 interface

<device busclass="0300" vendor="1002" model="4654" model_name="Mach64 VT [264VT FT]"> 

      XFree86                                               
                                                                 
        ati                                               

      XF86_Mach64                                           

</device>                                                                             

     ----------------------------------------------------------------------

6.3. Locally-Defined Interfaces

   Progeny recommends that publicly distributed Discover XML files avoid
   using the interface name local; that is, a class attribute value of local
   in a top-level data element. This means that data paths such as
   local/foo/bar should not be defined in a public Discover XML file, but
   both foo/bar/local and foo/local/bar are okay.

   The intention is to reserve this part of the namespace for users'
   experiments with defining their own - and possibly future, widely adopted
   - interface definitions for Discover data. An interface definition could
   thus be "beta tested" by a person or organization to ensure that it is
   efficiently structured before it is unleashed upon the world elsewhere in
   the namespace, where people may write tools that expect to be able to
   resolve the interface definition's data paths.

   Likewise, Progeny recommends that authors of applications that use
   Discover avoid traversing into a top-level local data element, which may
   impose an undesirable support burden on the designers of the interface
   while they are still working out their design. (The application also may
   not find the data it desires, or may not get back what it expects.)

     ----------------------------------------------------------------------

                          Chapter 7. Why Order Matters

   When searching device elements, the first exact match will be selected.
   Subsequent matches are ignored.

   Specifically, three comparisons are made:

    1. The hardware must provide identification that matches attributes of
       the device element. As an example, a PCI device supplies numeric
       vendor and model identifiers, which are used to match the model and
       vendor attributes.

    2. The class attributes of child data elements must match the data path
       as given to the library for searching.

    3. The first version range, if any, associated with the nested data
       elements must encompass any version provided by the client.

   Example 7-1. Matching device elements

   Assume that the path linux/module/name is provided, along with a version
   of 2.4.2. The following is sample data; the device elements may be from
   the same or different data files.

<device busclass="0000" vendor="102f" model="5555" model_name="100VG ethernet"> 
  (1)                                   
                                                           
        vg100                                          

  (2)                                   
                                                            
        vg100                                          
        io=0x300                                    

</device>                                                                        
                                                                                 
<device busclass="0000" vendor="102f" model="5555" model_name="100VG ethernet">  
  (3)                                                        
                                                            
        vg100new                                       

  (4)                                   
                                                            
        vg100old                                       

</device>                                                                        

   (1)
           This item is the first one scanned, and would match, except that
           the requested data path includes "module" as a component, not
           "modules" as specified here.
   (2)
           This item doesn't match because the provided range is outside the
           limits defined by the element. (2.4.2 is not greater than or equal
           to 2.0 and less than 2.2.)
   (3)
           This item matches because no range is given, so "vg100new" is the
           value returned.
   (4)
           This is the nearest match, but the Discover library will never
           select it because its previous sibling has no version range, and
           thus will catch any version provided.

     ----------------------------------------------------------------------

                        Chapter 8. Using Data Versioning

8.1. Specifying a Range

   Because multiple versions of a software interface often are in
   simultaneous deployment, Progeny recommendeds that the upper bound of a
   data element's version attribute be defined as the first version that is
   inconsistent with the information provided within it, and that the upper
   end of the interval be open (terminated with a parenthesis). As an
   example, suppose we know that the name of the Linux kernel module to drive
   the RealTek RTL-8139 Ethernet device was rtl8139 in the 2.2 kernel series
   and 8139too in the 2.4 series. To express this, we would say the
   following:

   Example 8-1. Using the version attribute of the data element

   <device_list bus="pci">                                                    
   <device busclass="0200" model="8139" model_name="RTL-8139" vendor="10ec">  

          8139too                                   

          rtl8139                                   

   </device>                                                                  
   </device_list>                                                             

   In the first data element, for instance, we would not use a version
   attribute of [2.2.0,2.2.19] because it is needlessly specific. What
   happens if the Linux kernel developers release Linux kernel 2.2.20? By
   saying [2.2,2.4), we "catch" everything in the kernel 2.2 series[2] -
   past, present, and future.

     ----------------------------------------------------------------------

8.2. How the Discover Library Matches a Range

   The data files will be searched in order; the first data path that matches
   the version range or doesn't have a version range will be returned.

   Recalling the discussion in Section 5.3.2, if you want the first data
   element matching the requested data path to also be the "fallback" element
   if no version range applies, you can duplicate that data element and place
   it at the end. However, a better practice is to make certain that all
   reasonable versions will match one of the ranges, and that the first range
   listed has an open-ended high end, such as [2.4, inf) for Linux kernel
   modules in Example 8-1. This will have the effect of "assuming" that all
   unversioned requests for linux data will be for Linux kernel 2.4 or later.

                            III. Command-Line Tools

   Table of Contents

   9. discover Manual Page

                discover -- hardware detection utility

   10. discover.conf Manual Page

                discover.conf -- configuration file format for discover(1)

   11. discover-modprobe Manual Page

                discover-modprobe -- kernel module loading using discover(1)

   12. discover-modprobe.conf Manual Page

                discover-modprobe.conf -- configuration file for
                discover-modprobe(5)

     ----------------------------------------------------------------------

                        Chapter 9. discover Manual Page

                                    discover

Name

   discover -- hardware detection utility

Synopsis

   discover [DATA_OPTIONS] [DISPLAY_OPTIONS] [--bus-summary] [bus...]

   discover [DATA_OPTIONS] [DISPLAY_OPTIONS] --type-summary [type...]

   discover [DATA_OPTIONS] --data-path=path/to/data...
   [--data-version=version] [--normalize-whitespace] [--format=format string]
   [type | id...]

   DATA_OPTIONS

              * -d | --disable-bus=bus

              * -e | --enable-bus=bus

              * --insert-url=url

              * --append-url=url

              * -v | --verbose

   DISPLAY_OPTIONS

              * --model | --no-model

              * --model-id | --no-model-id

              * --vendor | --no-vendor

              * --vendor-id | --no-vendor-id

Description

   discover provides an extensible hardware detection and reporting
   interface. Hardware information is stored in an XML data format and can be
   retrieved across the network.

   Fundamental modes of operation:

     * Display a list of hardware devices based on type of device or system
       bus on which the devices reside, via --type-summary or --bus-summary
       (the latter of which is the default behavior).

     * Query specified data for attached hardware, via --data-path.

Options

   -h | --help

           Display a simple help message.

   -v | --verbose

           Instruct the tool to provide feedback as it operates. This will
           affect the output as discover parses certain arguments, so this
           should appear early in the command line.

   -V | --version

           Display the tool name and version.

   -b | --bus-summary

           This is the default behavior: Display basic information regarding
           all devices on the appropriate buses. See Selecting Buses.

   -t | --type-summary

           Summarize devices by class of hardware. Examples of valid device
           types include broadband, fixeddisk, display, and network. See
           Device Types.

   --data-path=path/to/data

           Query matching devices for detailed information. Device-specific
           data is stored in a hierarchical fashion, and the query argument
           comprises strings naming each level in that hierarchy.

           Typically, the top-level component of the data path will be the
           "platform" that will need the information, such as linux or
           xfree86. For example, to retrieve the Linux kernel module name for
           a piece of hardware, the --data-path argument would be
           linux/module/name.

           If multiple --data-path arguments are given and no format string
           (see --format) is provided, only the last path is used.

           See also the --data-version argument.

   --data-version=version

           Specify a version string for the platform that will use the
           information specified by the argument to --data-path.

           This string must be in dotted-decimal notation in order to be
           matched against a range of values, and thus may be shorter than
           the real version.

   --format=format string

           Dictate the output of the results of the queries specified by
           --data-path arguments. This format string should follow printf(3)
           specifications, although only %s and appropriate flags, precision,
           and width values are supported (or make sense); literal text and
           %% can also be used. The behavior when the string is poorly
           formatted is undefined. See also --normalize-whitespace.

   -d | --disable-bus=bus

           Use this option to override the list of buses to scan by default
           as defined in discover.conf. Use all as an argument to disable all
           buses; this is useful only if followed by --enable-bus (or -e)
           arguments.

   -e | --enable-bus=bus

           Specify a bus to be scanned.

   --insert-url=url

           Insert a URL at the head of the list of network resources to
           include in the search for hardware information. Earlier data
           overrides later data; to override the local data sources, insert
           URLs into the list. See also --append-url.

   --append-url=url

           Append a URL to the end of the list of network resources to search
           for hardware information. See also --insert-url.

   --model

           Include the model description in summary information. This is
           enabled by default.

   --model-id

           Include the numeric model identifier in summary information.

   --no-model

           Do not include the model description in summary information.

   --no-model-id

           Do not include the numeric model identifier in summary
           information. This is the default.

   --vendor

           Include the vendor description in summary information. This is
           enabled by default.

   --vendor-id

           Include the numeric vendor identifier in summary information.

   --no-vendor

           Do not include the vendor description in summary information.

   --no-vendor-id

           Do not include the numeric vendor identifier in summary
           information. This is the default.

   --normalize-whitespace

           Consolidate whitespace in the results of a --data-path query. The
           default is not to do so, which faithfully reproduces all text in
           the raw XML data.

           With this option enabled, leading and trailing whitespace is
           removed, and any consecutive internal whitespaces are compressed
           to a single space character.

Selecting Buses

   discover.conf defines two lists of system buses: one to scan by default
   (used by the discover command), and one never to scan (used by the
   Discover library).

   You can override and/or extend the list of default buses with
   --disable-bus and --enable-bus. The list of buses not to scan cannot be
   overridden without changing discover.conf, so that list should be used
   only for buses that may be dangerous to probe.

   Both arguments take the string "all" as a value.

   If a bus summary is being performed, which is indicated either by the
   presence of --bus-summary or the absence of --type-summary and
   --data-path, any unattached arguments on the command line will be
   interpreted as the only buses to scan. This is equivalent to using
   --disable-bus all before invoking --enable-bus for the buses of interest.

   The following buses are currently supported by Discover:

     * ata

     * pci

     * pcmcia

     * scsi

     * usb

Device Types

   Discover defines its own device types, to which the device types used by
   each bus are mapped. Discover currently recognizes the following device
   types:

     * audio

       A device capable of producing an analog or digital sound signal is an
       audio device. Typically, any device commonly referred to as a "sound
       card" is classified by Discover as an audio device.

     * bridge

       A device that provides access to devices of a different type, commonly
       on a different bus, is a bridge device. For instance, consumer PCI
       chipsets often feature a bridge to ATA (also known as IDE) devices.

     * broadband

       An interface device to a computer communications network implemented
       on top of a technology not explicitly designed for that purpose is a
       broadband device. Examples include ISDN terminal adapters as well as
       DSL and cable "modems"; analog phone-line modems are not included in
       this classification (see "modem" below).

     * display

       A device controlled by the host machine's CPU and capable of producing
       an analog or digital video signal for output purposes is a display
       device. Typically, any device commonly referred to as a "video card"
       is classified by Discover as a display device.

     * fixeddisk

       A high-speed, fixed magnetic storage device such as a hard disk drive
       is a fixeddisk device. Removable media devices such as floppy disk
       drives, CD-ROM drives, magneto-optical devices, tape drives, and
       Compact Flash card readers are not included in this classification.

     * humaninput

       A device that receives tactile input from a person for the purpose of
       directing a computer's activity is a humaninput device. Examples
       include keyboards, mice, trackballs, joysticks, gamepads, digital
       tablets manipulated with a stylus or finger, and so forth. Input
       devices that rely upon non-tactile means of determining a person's
       intent, such as speech-recognition devices or cameras, are not
       included in this classification.

     * imaging

       A device that captures still images for input purposes is an imaging
       device. Scanners and digital cameras are examples of imaging devices.
       Motion-capture devices such as television tuner cards, webcams, and
       digital video cameras are not included in this classification.

     * miscellaneous

       Any device that cannot logically be classified as another device type
       is a miscellaneous device.

     * modem

       An analog phone-line modulator/demodulator (modem) is classified by
       Discover as a modem device. No other kind of device is so classified.

     * network

       An interface device to a conventional computer data communications
       network that does not require the use of a terminal adapter is a
       network device. For example, Ethernet and Token Ring network interface
       cards are network devices. Analog phone-line modems; terminal adapters
       for technologies such as ISDN and DSL; and "cable modems" are not
       "network" devices.

     * optical

       An optical-technology storage device, often using read-only media, is
       an optical device. By far the most common examples of these devices
       are CD-ROM and DVD-ROM drives, including versions of these drives that
       can "burn" (write to) optical discs.

     * printer

       A device that renders visual output in a permanent or semi-permanent
       manner to a physical medium is a printer. Typically, any device
       colloquially referred to as a "printer" is also classified by Discover
       as a printer.

     * removabledisk

       Storage devices that feature removable media using just about any
       technology except that of magnetic tape, CD-ROM, and DVD-ROM drives
       are removabledisk devices. Examples include floppy disk drives,
       magneto-optical drives, and Compact Flash card readers.

     * tape

       A sequential-access mass storage device using magnetic tape is a tape
       device. Commonly used for archival and backup purposes, DAT drives are
       examples of tape devices.

     * video

       A device that produces a real-time digital video signal for input
       purposes is a video device. Webcams, digital video cameras, and
       television tuners are examples of video devices. Note that still
       digital cameras with "movie" capability are not considered video
       devices unless they can transmit the live video signal to the host in
       real time.

Examples

   Example 9-1. Scan the local buses

   # discover                                                                 
   Intel Corporation 82815 Chipset Host Bridge and Memory Controller Hub      
   unknown unknown                                                            
   unknown unknown                                                            
   unknown unknown                                                            
   Intel Corporation 82815 Chipset IDE controller                             
   Intel Corporation 82815 Chipset USB (A)                                    
   Intel Corporation 82815 System Management bus controller                   
   ATI Technologies, Inc. Rage 128 Pro GL [PF]                                
   3Com Corporation 3c905C-TX [Fast Etherlink]                                
   Ensoniq ES1371 [AudioPCI-97]                                               
   unknown unknown                                                            

   Example 9-2. View PCI video cards

   # discover -v --type-summary --disable-bus all --enable-bus pci display    
   Disabled pci                                                               
   Disabled pcmcia                                                            
   Disabled scsi                                                              
   Disabled usb                                                               
   Enabled pci                                                                
   Loading XML data... pci Done                                               
   Scanning buses... pci Done                                                 
   ATI Technologies, Inc. Rage 128 Pro GL [PF]                                

   Example 9-3. Query for the driver module for XFree86 server version 4.2.0

# discover --data-path=xfree86/server/device/driver --data-version=4.2.0 display 
ati                                                                              

   Example 9-4. Get model and vendor information by type

   $ discover -t --no-model                                                   
   Intel Corporation                                                          
   NVIDIA Corporation                                                         
   3Com Corporation                                                           
   $ discover -t --no-vendor                                                  
   82815 System Management bus controller                                     
   Vanta [NV6]                                                                
   3c905C-TX [Fast Etherlink]                                                 

Files

   /etc/discover.conf.d

           The directory containing configuration files that control the
           default behavior for both the discover tool and the Discover
           library.

   file:///lib/discover/list.xml

           An XML file containing URLs with hardware information. This list
           can be extended with --append-url and --extend-url.

Authors

   Josh Bressers, John R. Daily, and G. Branden Robinson developed the
   current implementation of Discover for Progeny Linux Systems.

   The Linux implementation of the system-dependent interfaces is derived
   from detect, by MandrakeSoft SA.

See Also

   discover.conf(5), discover-modprobe(8)

     ----------------------------------------------------------------------

                     Chapter 10. discover.conf Manual Page

                                 discover.conf

Name

   discover.conf -- configuration file format for discover(1)

Description

   Discover looks for configuration files in a configuration directory,
   containing a number of files. These define the system buses that should be
   scanned by default, those that should never be scanned, and the URLs for
   hardware data files beyond the local copy provided with the software.

   The file format is XML; the DTD is provided with the Discover software,
   and can be used for informational or validation purposes.

Examples

   Example 10-1. Establishing default buses to scan

   
<?xml version="1.0"?>                                                     
                                                                              
   <!DOCTYPE conffile SYSTEM "conffile.dtd">                                  
                                                                              
   <conffile>                                                                 
     <busscan scan="default">                                                 
       <bus name="ata"/>                                                      
       <bus name="pci"/>                                                      
       <bus name="pcmcia"/>                                                   
       <bus name="scsi"/>                                                     
       <bus name="usb"/>                                                      
     </busscan>                                                               
   </conffile>                                                                

   Example 10-2. A more complex example

   
<?xml version="1.0"?>                                                     
                                                                              
   <!DOCTYPE conffile SYSTEM "conffile.dtd">                                  
                                                                              
   <conffile>                                                                 
     <busscan scan="default">                                                 
       <bus name="ata"/>                                                      
       <bus name="pci"/>                                                      
       <bus name="pcmcia"/>                                                   
       <bus name="usb"/>                                                      
     </busscan>                                                               
                            
     <busscan scan="never">                                                   
       <bus name="scsi"/>                                                     
     </busscan>                                                               
     <data-sources>                                                           
       <data-source url="http://www.example.com/discover/xfree86.xml"         
                    label="Updated XFree86 hardware information">             
     </data-sources>                                                          
   </conffile>                                                                

Authors

   Josh Bressers, John R. Daily, and G. Branden Robinson developed the
   current implementation of Discover for Progeny Linux Systems.

   The Linux implementation of the system-dependent interfaces is derived
   from detect, by MandrakeSoft SA.

See Also

   discover(1)

     ----------------------------------------------------------------------

                   Chapter 11. discover-modprobe Manual Page

                               discover-modprobe

Name

   discover-modprobe -- kernel module loading using discover(1)

Synopsis

   discover-modprobe [-n] [-v]

Description

   discover-modprobe loads kernel modules identified by discover. It will
   typically be invoked automatically at boot time.

Options

   -n

           Echo the modprobe invocations instead of running them.

   -v

           Be verbose.

Files

   /etc/discover-modprobe.conf

           This configuration file defines the types of modules to load by
           default, and specific modules not to load.

   /var/lib/discover/crash

           A crash file written and erased each time discover-modprobe
           attempts to load a module. If the file lingers, the computer is
           assumed to have crashed while loading that module, and the module
           name is added to discover-modprobe.conf as a module to skip in the
           future.

See Also

   discover-modprobe.conf(5), modprobe(8), discover(1)

     ----------------------------------------------------------------------

                 Chapter 12. discover-modprobe.conf Manual Page

                             discover-modprobe.conf

Name

   discover-modprobe.conf -- configuration file for discover-modprobe(5)

Description

   discover-modprobe.conf is the configuration file for discover-modprobe,
   which is responsible for retrieving and loading kernel modules.

   Warning This file is a shell script, and as such is subject to a string    
           variable assignment syntax. No space is allowed between the        
           variable name, the equal (=) sign, and the value(s) assigned. If   
           multiple values are to be assigned, the list must be               
           space-delimited with surrounding quotes.                           

   Two directives can be used in this file: types and skip. Both can be
   defined multiple times.

   types

           This describes the classes of hardware that should be scanned and
           queried.

   skip

           These modules should never be loaded. See the "Files" section for
           details on the mechanism for generating these entries
           automatically.

Files

   /var/lib/discover/crash

           A crash file written and erased each time discover-modprobe
           attempts to load a module. If the file lingers, the computer is
           assumed to have crashed while loading that module, and the module
           name is added to discover-modprobe.conf as a module to skip in the
           future.

See Also

   discover-modprobe(8), modprobe(8), discover(1)

                                  IV. Library

   Table of Contents

   13. The Discover Library

                13.1. Library Design Principles

                13.2. Discover Data Sources

                13.3. The Bus Map

                13.4. Scanning the System

                13.5. Using discover_device_t Structures

   14. System Dependencies

                14.1. API

     ----------------------------------------------------------------------

                        Chapter 13. The Discover Library

13.1. Library Design Principles

   Lazy allocation is used throughout Discover. This means that there are no
   "init" functions, and no functions to scan the bus. Instead, retrieval
   functions scan or initialize as necessary. Each of these retrieval
   functions has an equivalent function for freeing the allocated memory.
   This is valuable to long-lived processes to aid in memory management, but
   even short-lived processes may want to use them to force reloading of the
   information.

     ----------------------------------------------------------------------

13.2. Discover Data Sources

   Discover knows about one data source by default: the local data from the
   discover-data package. Additional sources can be added with the
   discover_conf_append_url and discover_conf_insert_url functions. As their
   names suggest, they append or insert URLs on the data source list. Earlier
   data overrides later data; to override the local data sources, insert
   URLs.

     ----------------------------------------------------------------------

13.3. The Bus Map

   Most high-level operations begin at the bus map. Bus maps
   (discover_bus_map_t) are retrieved with calls to discover_conf_get_bus_map
   or discover_conf_get_bus_map_by_name. discover_conf_get_bus_map returns an
   array of maps, one for each supported bus, with the last element being all
   0s. discover_conf_get_bus_map_by_name returns the map for the named bus.
   The map contains pointers to all the functions that operate on the bus, as
   well as the scan_default variable, which determines whether the bus is
   scanned by default. There is also a scan_never variable, but it is for
   internal use only. The name of the bus is stored in the name variable.

   The following functions are available in the bus map. The "get" functions
   take a single discover_error_t argument and return a list of
   discover_device_t structures, while the "free" functions take no arguments
   and return no value.

   get_devices

           Retrieve the list of devices found on this bus. Returns NULL if
           the bus is not present on the system, or if no devices are
           attached to it.

   xml_get_busclasses

           Retrieve the list of busclasses for this bus (from the XML data
           sources).

   xml_get_devices

           Retrieve the list of devices for this bus (from the XML data
           sources). Note that this is the list of devices that Discover
           knows about, not the list of devices present on the system.

   xml_get_vendors

           Retrieve the list of vendors for this bus (from the XML data
           sources).

   xml_get_busclass_urls

           Retrieve the list of URLs from which busclass data is retrieved.
           This function is probably not useful to most clients.

   xml_get_device_urls

           Retrieve the list of URLs from which device data is retrieved.
           This function is probably not useful to most clients.

   xml_get_vendor_urls

           Retrieve the list of URLs from which vendor data is retrieved.
           This function is probably not useful to most clients.

   free_devices

           Free the list of devices.

   xml_free_busclasses

           Free the list of busclasses.

   xml_free_devices

           Free the list of devices (the XML data, not the list of devices
           found on the system).

   xml_free_vendors

           Free the list of vendors.

   xml_free_busclass_urls

           Free the list of busclass URLs.

   xml_free_device_urls

           Free the list of device URLs.

   xml_free_vendor_urls

           Free the list of vendor URLs.

     ----------------------------------------------------------------------

13.4. Scanning the System

   Discover provides a few ways to scan the system for information.

   You can walk the bus map:

   for (i = 0; busmap[i].name; i++) {                                         
       if (busmap[i].scan == DISCOVER_SCAN_DEFAULT) {                         
           devices = busmap[i].get_devices(&status);                          
           check_status(status);                                              
           do_something_cool(devices);                                        
       }                                                                      
   }                                                                          

   You can scan a specific bus:

   devices = discover_get_pci_devices(&status);                               
   check_status(status);                                                      
   do_something_cool(devices);                                                

   Perhaps most usefully, you can scan for devices of a specific type:

   devices = discover_device_find("video", &status);                          
   check_status(status);                                                      
   do_something_video(devices);                                               

     ----------------------------------------------------------------------

13.5. Using discover_device_t Structures

   Now that you have some device structures, what can you do with them? The
   most interesting operation is retrieving data with
   discover_device_get_data. Also available are
   discover_device_get_vendor_name, discover_device_get_model_name,
   discover_device_get_model_id, and discover_device_get_vendor_id.

   discover_device_get_data takes a data path and a version number and
   searches for the first data structure that matches.

   discover_device_get_vendor_name returns the human-readable name for the
   device's vendor.

   discover_device_get_model_name returns the human-readable name for the
   device's model.

   discover_device_get_model_id returns the bus-specific ID for the device
   model.

   discover_device_get_vendor_id returns the bus-specific ID for the device
   vendor.

     ----------------------------------------------------------------------

                        Chapter 14. System Dependencies

14.1. API

   The system-dependent code (sysdeps) that must be custom-written for each
   operating system conforms to a very simple API. Discover invokes
   _discover_get_busname_raw() with no arguments, and expects a linked list
   of discover_sysdep_data_t structures in return.

   The discover_sysdep_data_t structures should contain as much descriptive
   information as they can regarding the devices discovered. Specifically,
   the three pieces of information desired are the busclass (device type),
   vendor identifier, and model identifier, which is a unique identification
   string that the vendor has provided for the given piece of hardware.

   Example 14-1. Linux PCI sysdep code

   #include <config.h>                                                        
                                                                              
   #include <stdio.h>                                                         
   #include <stdlib.h>                                                        
                                                                              
   #include <sysdep.h>                                                        
                                                                              
   discover_sysdep_data_t *                                                   
   _discover_get_pci_raw(void)                                                
   {                                                                          
       FILE *f;                                                               
       char *line = NULL;                                                     
       size_t len = 0;                                                        
       discover_sysdep_data_t *head = NULL, *node, *last = NULL;              
       unsigned int id;                                                       
                                                                              
       if ((f = fopen(PATH_PROC_PCI, "r"))) {                                 
           while (getline(&line, &len, f) >= 0) {                             
               if (line[0] == '\n' || line[0] == '#') {                       
                   continue;                                                  
               }                                                              
                                                                              
               node = _discover_sysdep_data_new();                            
               sscanf(line, "%*04x\t%08x", &id);                              
               node->vendor = (id >> 16);                                     
               node->model = id & 0xffff;                                     
                                                                              
               if (head == NULL) {                                            
                   head = node;                                               
                   last = head;                                               
               } else {                                                       
                   last->next = node;                                         
                   last = node;                                               
               }                                                              
           }                                                                  
           free(line);                                                        
           fclose(f);                                                         
       }                                                                      
       return head;                                                           
   }                                                                          

     ----------------------------------------------------------------------

                       Appendix A. Discover API Reference

   The API reference is here.

     ----------------------------------------------------------------------

                            Appendix B. Discover DTD

   
                                                        
                                                                              
   <!ELEMENT discover-data (location)*>                                       
                                                                              
   <!ELEMENT location EMPTY>                                                  
   <!ATTLIST location bus          NMTOKEN #REQUIRED                          
                      type         NMTOKEN #REQUIRED                          
                      url          CDATA   #REQUIRED>                         
                                                                              
   <!ELEMENT busclass_list (busclass)*>                                       
   <!ATTLIST busclass_list bus NMTOKEN #REQUIRED>                             
                                                                              
   <!ELEMENT busclass EMPTY>                                                  
   <!ATTLIST busclass id           NMTOKEN #REQUIRED                          
                      name         NMTOKEN #REQUIRED>                         
                                                                              
   <!ELEMENT vendor_list (vendor)*>                                           
   <!ATTLIST vendor_list bus NMTOKEN #REQUIRED>                               
                                                                              
   <!ELEMENT vendor EMPTY>                                                    
   <!ATTLIST vendor id             CDATA #REQUIRED                            
                    name           CDATA #REQUIRED>                           
                                                                              
   <!ELEMENT device_list (device)*>                                           
   <!ATTLIST device_list bus NMTOKEN #REQUIRED>                               
                                                                              
   <!ELEMENT device (data)*>                                                  
   <!ATTLIST device busclass       NMTOKEN #REQUIRED                          
                    model          CDATA #DEFAULT default                     
                    model_name     CDATA   #REQUIRED                          
                    vendor         CDATA #REQUIRED>                           
                                                                              
   <!ELEMENT data (#PCDATA|data)*>                                            
   <!ATTLIST data class                NMTOKEN #REQUIRED                      
                  version          CDATA   #IMPLIED>                          
                                                                              
                                       
                                                                              
                                                                              

     ----------------------------------------------------------------------

                  Appendix C. Discover Configuration File DTD

   
                                                         
                                                                               
   <!ELEMENT conffile (busscan*,data-sources?)>                                
                                                                               
   <!ELEMENT data-sources (data-source)*>                                      
   <!ELEMENT data-source EMPTY>                                                
   <!ATTLIST data-source url          CDATA #REQUIRED                          
                         label        CDATA #IMPLIED                           
                         place        NMTOKEN #IMPLIED>                        
                                                                               
   <!ELEMENT busscan (bus)*>                                                   
                                                                               
    
    
    
    
   <!ATTLIST busscan scan (default|never) #REQUIRED>                           
                                                                               
   <!ELEMENT bus EMPTY>                                                        
   <!ATTLIST bus name              NMTOKEN #REQUIRED>                          
                                                                               
                                                                               

     ----------------------------------------------------------------------

                Appendix D. Licensing Issue on the Linux Sysdeps

   It should be noted that the Linux-specific files in the sysdeps/linux
   directory of the source distribution are derived from code written for the
   Detect library by MandrakeSoft SA, and are licensed under the GNU
   Project's General Public License (GPL).

   Note that section 2 of the GPL places requirements on derived works that
   prevent licensees from exercising some of the permissions granted under
   the license on the rest of Discover. However, not everyone who modifies or
   distributes Discover will necessarily be subject to the terms of the GPL.
   If you do not compile, use, or distribute the Linux sysdeps (for instance,
   if you are building Discover for FreeBSD), then the license terms on them
   do not attach.

   We realize, however, that it is desirable that all of Discover be under
   the the same license terms. There are a few possible solutions to this
   problem:

     * If you do not need the Linux sysdeps, you can delete them from your
       copy of Discover.

     * You can rewrite the Linux sysdeps. The resulting code will be your
       work, so the only limitations on you will be those imposed by
       Discover's license. If you do so, we encourage you to license your
       rewrite under the same terms as the rest of Discover - in that event,
       Progeny will be happy to incorporate your code into a future release
       of Discover.

     * You can contact MandrakeSoft SA and negotiate a different license to
       their code that is used in the Linux sysdeps.

     * You can contact MandrakeSoft SA and attempt to persuade them to
       relicense their code that is used in the Linux sydeps under the terms
       used by the rest of Discover. (MandrakeSoft SA would not have to
       abandon or assign their copyright.) If you succeed in this effort,
       please let Progeny know and we will update the license terms on our
       copy of the MandrakeSoft SA code.

     * You can wait; eventually Progeny employees, or some volunteer, will
       rewrite the Linux sysdeps and license them under the terms that the
       rest of Discover uses.

   Note The foregoing discussing is not legal advice and makes no claim to be 
        such. It is a layperson's understanding of the licensing issues from  
        a software developer's perspective. Progeny makes no warranties or    
        guarantees as to the accuracy of the above analysis in a legal        
        context. If you require a professional legal opinion, consult         
        attorneys specializing in copyright and licensed to practice in the   
        jurisdictions of interest to you or to your organization.             

  Notes

   [1] Other protocols such as FTP are available but deprecated; Discover     
       uses integrity verification mechanisms such as MD5 checksums in the    
       HTTP protocol.                                                         
   [2] We would say [2.2,2.3) instead, but, like many Free Software projects, 
       the Linux kernel uses odd minor version numbers to denote unstable,    
       development series of the software, and even minor version numbers to  
       denote stable, production series of the software. In the example,      
       then, we arbitrarily treat all 2.3 series kernels the same as 2.2      
       kernels.                                                               
