Add shim for libc::sysconf(libc::_SC_NPROCESSORS_CONF)

[frewsxcv]

libc::sysconf(libc::_SC_NPROCESSORS_CONF) is used by AArch64 devices to get the number of CPUs in the num_cpus crate:

https://github.com/seanmonstar/num_cpus/blob/b423db0a698b035914ae1fd6b7ce5d2a4e727b46/src/lib.rs#L337-L342

[RalfJung]

Thanks for the PR!

We should find some way to test this. What target triple would be suited to trigger this code path in num_cpus?

[RalfJung]

Looks like you are on aarch64-apple-darwin. So I propose you change this line to test that target instead:

miri/ci.sh

Line 50 in 6fdda8a

MIRI_TEST_TARGET=x86_64-apple-darwin run_tests

[frewsxcv]

@RalfJung should i change that line, or add a new line?

[RalfJung]

Changing it is okay I think, we don't need to test that same target tripled on all host platforms.

[frewsxcv]

Changing it is okay I think, we don't need to test that same target tripled on all host platforms.

Done in 36ce776

[frewsxcv]

I see the test failures, and I don't think I have the time to address all of them. Can an issue be opened and this be done in a separate pull request?

[RalfJung]

Looks like some more work is needed to support aarch64, yeah. I should have time today or tomorrow to look into that and will push to this PR, if you don't mind.

[frewsxcv]

Looks like some more work is needed to support aarch64, yeah. I should have time today or tomorrow to look into that and will push to this PR, if you don't mind.

Yeah sounds good to me. Thanks so much 🙇🏻

[RalfJung]

@bors r+

[bors]

📌 Commit 7d8f8c4 has been approved by RalfJung

[bors]

⌛ Testing commit 7d8f8c4 with merge 5e9bf46...

[bors]

☀️ Test successful - checks-actions
Approved by: RalfJung
Pushing 5e9bf46 to master...