Detect x32 userspace ABI on 64-bit kernel

[pradyunsg]

Given pypa/pip#6908, do we want to put try to get this into pypa/packaging instead?

Originally posted by @chrahunt in pypa/pip#5391 (comment)

This would be a fix related to pypa/pip#4962.

[pradyunsg]

Is this still relevant?

[uranusjr]

I believe so. packaging.tags still assumes i686 when a 32-bit interpreter is run on a 64-bit platform.

packaging/packaging/tags.py

Lines 419 to 423 in 5984e3b

	if is_32bit:
	if linux == "linux_x86_64":
	linux = "linux_i686"
	elif linux == "linux_aarch64":
	linux = "linux_armv7l"

[ehashman]

FWIW I think the right way to do this (back when I was working on a fix) was to look at whatever ELF interpreter Python was called with and use that to pick the arch. This would require parsing the Python ELF...

[uranusjr]

We are already parsing ELF for both manylinux and musllinux detection so why not :p

[uranusjr]

How do we start building this? Parsing the ELF is the easy part, but making sense of the data requires more research. Is there a list of machine and ABI information of common platforms available?

[ehashman]

https://wiki.debian.org/X32Port#Detecting_X32 is the official answer, I think.

The unofficial answer I was going for is looking at the path of the ELF interpreter Python was built with. On an x32 system, there should always be x32 (rather than i386) in the path... either it's in /libx32 or symlinks to something with x32 in the filename in /lib. Hacky but probably reliable.