# llvm-offload-binary - LLVM Offload Binary Packager

## SYNOPSIS

llvm-offload-binary [options] [input files…]

## DESCRIPTION

llvm-offload-binary is a utility for bundling multiple device object files into a single binary container. The resulting binary can then be embedded into the host section table to form a fat binary containing offloading code for different targets. Conversely, it can also extract previously bundled device images.

The binary format begins with the magic bytes `0x10FF10AD`, followed by a version and size. Each binary contains its own header, allowing tools to locate offloading sections even when merged by a linker. Each offload entry includes metadata such as the device image kind, producer kind, and key-value string metadata. Multiple offloading images are concatenated to form a fat binary.

## EXAMPLE

    # Package multiple device images into a fat binary:
    $ llvm-offload-binary -o out.bin \
          --image=file=input.o,triple=nvptx64,arch=sm_70

    # Extract a matching image from a fat binary:
    $ llvm-offload-binary in.bin \
          --image=file=output.o,triple=nvptx64,arch=sm_70

    # Extract and archive images into a static library:
    $ llvm-offload-binary in.bin --archive -o libdevice.a

## OPTIONS

--archive

  When extracting from an input binary, write all extracted images into a static archive instead of separate files.

--image=<<key>=<value>,...>

  Specify a set of arbitrary key-value arguments describing an image. Commonly used optional keys include `arch` (e.g. `sm_70` for CUDA) and `triple` (e.g. nvptx64-nvidia-cuda).

-o <file>

  Write output to <file>. When bundling, this specifies the fat binary filename. When extracting, this specifies the archive or output file destination.

--help, -h

  Display available options. Use `--help-hidden` to show hidden options.

--help-list

  Display a list of all options. Use `--help-list-hidden` to show hidden ones.

--version

  Display the version of the llvm-offload-binary executable.

@<FILE>

  Read command-line options from response file <FILE>.

## BINARY FORMAT

The binary format is marked by the magic bytes `0x10FF10AD`, followed by a version number. Each created binary contains its own header. This allows tools to locate offloading sections even after linker operations such as relocatable linking. Conceptually, this binary format is a serialization of a string map and an image buffer.

Table 1 Offloading Binary Header
Type | Identifier | Description
--- | --- | ---
uint8_t | magic | The magic bytes for the binary format (0x10FF10AD)
uint32_t | version | Version of this format (currently version 1)
uint64_t | size | Size of this binary in bytes
uint64_t | entry offset | Absolute offset of the offload entries in bytes
uint64_t | entry size | Size of the offload entries in bytes

Each offload entry describes a bundled image along with its associated metadata.

Table 2 Offloading Entry Table
Type | Identifier | Description
--- | --- | ---
uint16_t | image kind | The kind of the device image (e.g. bc, cubin)
uint16_t | offload kind | The producer of the image (e.g. openmp, cuda)
uint32_t | flags | Generic flags for the image
uint64_t | string offset | Absolute offset of the string metadata table
uint64_t | num strings | Number of string entries in the table
uint64_t | image offset | Absolute offset of the device image in bytes
uint64_t | image size | Size of the device image in bytes

The entry table refers to both a string table and the raw device image itself. The string table provides arbitrary key-value metadata.

Table 3 Offloading String Entry
Type | Identifier | Description
--- | --- | ---
uint64_t | key offset | Absolute byte offset of the key in the string table
uint64_t | value offset | Absolute byte offset of the value in the string table

The string table is a collection of null-terminated strings stored in the image. Offsets allow string entries to be interpreted as key-value pairs, enabling flexible metadata such as architecture or target triple.

The enumerated values for `image kind` and `offload kind` are:

Table 4 Image Kind
Name | Value | Description
--- | --- | ---
IMG_None | 0x00 | No image information provided
IMG_Object | 0x01 | The image is a generic object file
IMG_Bitcode | 0x02 | The image is an LLVM-IR bitcode file
IMG_Cubin | 0x03 | The image is a CUDA object file
IMG_Fatbinary | 0x04 | The image is a CUDA fatbinary file
IMG_PTX | 0x05 | The image is a CUDA PTX file

Table 5 Offload Kind
Name | Value | Description
--- | --- | ---
OFK_None | 0x00 | No offloading information provided
OFK_OpenMP | 0x01 | The producer was OpenMP offloading
OFK_CUDA | 0x02 | The producer was CUDA
OFK_HIP | 0x03 | The producer was HIP
OFK_SYCL | 0x04 | The producer was SYCL

## SEE ALSO

clang(1), llvm-objdump(1)