binutils/readelf: build against msgpack, dump NT_AMDGPU_METADATA note contents
The AMDGPU HSA OS ABI (code object v3 and above) defines the
NT_AMDGPU_METADATA ELF note [1]. The content is a msgpack object
describing, among other things, the kernels present in the code object
and how to call them.
I think it would be useful for readelf to be able to display the content
of those notes. msgpack is a structured format, a bit like JSON, except
not text-based. It is therefore possible to dump the contents in
human-readable form without knowledge of the specific layout of the
note.
Add configury to binutils to optionally check for the msgpack C library
[2]. Add There is a new --with{,out}-msgpack configure flag, and the actual
library lookup is done using pkg-config.
If msgpack support is enabled, dumping a NT_AMDGPU_METADATA note looks
like:
If msgpack support is disabled, dump the contents as hex, as is done
with notes that are not handled in a special way. This allows one to
decode the contents manually (maybe using a command-line msgpack
decoder) if really needed.