Some functions and macros are found to have properties relevant to the Xen codebase. For this reason, the file docs/properties.json contains all the needed properties.

Here is an example of the properties.json file:

    {
       "version": "1.0",
       "content": [
          {
             "description": ""
             "type": "function",       // required
             "value:": "^printk*.$",   // required
             "properties":{
                "pointee_write": "1..2=never",
                "pointee_read": "",
                "taken": ""
                "attribute": ""
             }
          }
       ]
    }

Here is an explanation of the fields inside an object of the "content" array:

> - description: a brief description of why the properties apply

> - type: this is the kind of the element called: it may be either `macro` or `function`

> - value: must be a regex, starting with ^ and ending with $ and matching function fully qualified name or macro name.

> - properties: a list of properties applied to said function. Possible values are:

>   > - pointee_write: indicate the write use for call arguments that correspond to parameters whose pointee types are non-const
>   > - pointee_read: indicate the read use for call arguments that correspond to parameters whose pointee types are non-const
>   > - taken: indicates that the specified address arguments may be stored in objects that persist after the function has ceased to exist (excluding the returned value); address arguments not listed are never taken
>   > - attribute: attributes a function may have. Possible values are pure, const and noeffect.

>   pointee_read and pointee_write use a specific kind of argument, structured as pointee_arg=rw:

>   > - pointee_arg: argument index for callee. Index 0 refers to the return value, the indices of the arguments start from 1. It can be either a single value or a range.

>   > - rw: a value that's either always, maybe or never

>   >   > - always: for pointee_read: argument pointee is expected to be fully read in the function body, for pointee_write: argument pointee is fully initialized at function exit
>   >   > - maybe: for pointee_read: argument pointee may be expected to be read in the function body, for pointee_write: argument pointee may be written by function body
>   >   > - never: for pointee_read: argument pointee is not expected to be read in the function body, for pointee_write: argument pointee is never written by function body