## Summary
When installing packages on _very_ slow/overloaded systems it'spossible
to trigger bytecode compilation timeouts, which tends to happen in
environments such as Qemu (especially without KVM/virtio), but also on
systems that are simply overloaded. I've seen this in my Nix builds if I
for example am compiling a Linux kernel at the same time as a few other
concurrent builds.
By making the bytecode compilation timeout adjustable you can work
around such issues. I plan to set `UV_COMPILE_BYTECODE_TIMEOUT=0` in the
[pyproject.nix
builders](https://pyproject-nix.github.io/pyproject.nix/build.html) to
make them more reliable.
- Related issues
* https://github.com/astral-sh/uv/issues/6105
## Test Plan
Only manual testing was applied in this instance. There is no existing
automated tests for bytecode compilation timeout afaict.
Closes#14262
## Description
Adds `UV_LIBC` environment variable and implements check within
`Libc::from_env` as recommended here:
https://github.com/astral-sh/uv/issues/14262#issuecomment-3014600313
Gave this a few passes to make sure I follow dev practices within uv as
best I am able. Feel free to call out anything that could be improved.
## Test Plan
Planned to simply run existing test suite. Open to adding more tests
once implementation is validated due to my limited Rust experience.
Extends https://github.com/astral-sh/uv/pull/13841 — I'll drop that
commit later after that pull request merges but it's small.
I find the split into a "Configuration" section awkward and don't think
it's helping us. Everything moved into the "Concepts" section, except
the "Environment variables" page which definitely belongs in the
reference and the "Installer" page which is fairly niche and seems
better in the reference.
Before / After
<img
src="https://github.com/user-attachments/assets/80d8304b-17da-4900-a5f4-c3ccac96fcc5"
width="400">
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