uclibc support #1603

skrap · 2021-12-07T22:06:21Z

uclibc is a libc alternative (peer to glibc and musl) which is used in low-resource embedded linux applications.

It's supported in rust as the target_env of several tier 3 targets, but nix currently doesn't build. This patch provides a few customizations to get uclibc building.

To test:

Get nightly rust
Follow directions for getting a cross toolchain and env setup here: https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/armv7-unknown-linux-uclibceabihf.md

Thanks for your consideration!

rtzoeller · 2021-12-08T00:15:12Z

Thanks! Changes LGTM, although I didn't run the tests. A few thoughts....

Is armv7-unknown-linux-uclibceabihf the primary target you are intending to support with these changes? I tried building with some of the other uclibc targets and had mixed success: only armv7-unknown-linux-uclibceabihf and armv5te-unknown-linux-uclibceabi build successfully, while the mips, mipsel, and x86_64 targets fail to build.
- If yes we might consider adding armv7-unknown-linux-uclibceabihf to the list of targets we build for, similar to how we support other tier 3 targets like x86_64-unknown-dragonfly using -Zbuild-std. It seems like the effort to support uclibc is likely low for any individual PR, but that the build could easily break if we aren't validating it.
We'll want to squash/rebase the commits before merging. This doesn't necessarily need to happen now, as I imagine we'll hold off on submitting this until after the 0.23.1 release, and more changes could be required.

skrap · 2021-12-08T00:42:38Z

Thanks!

Is armv7-unknown-linux-uclibceabihf the primary target you are intending to support with these changes?

Yes, and I am doing so with corporate backing for a long-term product need. I would be glad to have this build running in CI to catch any errors early. I'm happy to make those changes if you point me in the right direction.

We'll want to squash/rebase the commits before merging.

Yes, that is fine. I can do that once the main branch is ready for these changes. Want to let me know with a comment here? Or some other way?

Thanks again!

asomers

I thought uclibc was used with RTOSes and microcontrollers, not Linux. Is it used with both?

asomers · 2021-12-11T22:25:25Z

src/sys/termios.rs

@@ -776,7 +776,7 @@ libc_bitflags! {
        ALTWERASE;
        IEXTEN;
        #[cfg(not(target_os = "redox"))]
-        EXTPROC;
+        EXTPROC as tcflag_t; // uclibc gets the type wrong


Is this due to a bug in libc?

Yes, it seems that libc's uclibc module doesn't have the right type for this item. We could accept this change here, pending a fix in libc, or I could try to get a libc change through first. Preferences?

Let's fix it in libc first.

rust-lang/libc#2592

Just checking in here- I'm pushing through the changes in libc but it's a bit slowed by some larger sibling changes. I am still definitely pursuing this PR :)

rtzoeller · 2021-12-11T23:12:50Z

I thought uclibc was used with RTOSes and microcontrollers, not Linux. Is it used with both?

I believe it is used with embedded devices which run Linux. https://gogs.waldemar-brodkorb.de/oss/uclibc-ng

rust-lang/libc has it alongside glibc and musl: https://github.com/rust-lang/libc/tree/master/src/unix/linux_like/linux

uclibc: fix type of EXTPROC. All of the other related constants are of type `tcflag_t`, but this one was wrong. This change will fix the build of `nix`. (Ref nix-rust/nix#1603)

lancethepants · 2022-01-18T22:11:48Z

Also looking forward to uclibc support as I am trying to bring up armv7-unknown-linux-uclibceabi as new tier3 target.
rust-lang/rust#92383
Tested this patch and it enabled me to compile my application. Not sure if I tested before or after #1571, but hopefully @skrap will keep on it.

rtzoeller · 2022-01-18T23:09:40Z

@skrap with rust-lang/libc#2615 being submitted, I believe this can likely be rebased and squashed.

Here's an example of how to build tier 3 targets in nix's CI:

nix/.cirrus.yml

Lines 280 to 282 in 18d1f62

    
           - name: OpenBSD x86_64 
        
             env: 
        
               TARGET: x86_64-unknown-openbsd

nix/bors.toml

Line 29 in 18d1f62

"OpenBSD x86_64",

skrap · 2022-01-19T14:30:48Z

Thanks! I'm working on this now. Unfortunately we'll need more changes to libc as well before this can succeed, but I'll be sure to reference this PR in any libc PRs so that those watching here can keep track of the progress if they like.

skrap · 2022-01-20T03:37:45Z

For now, I'm expecting CI to fail until:

libc cuts a new version to depend upon
I can track down the last few failures, which may be related to qemu user-space emulation inconsistencies

skrap · 2022-01-20T14:29:40Z

Ref https://gitlab.com/qemu-project/qemu/-/issues/829 which is causing failures in test_openat (and maybe more places) when testing under qemu user-space emulation.

skrap · 2022-01-20T16:00:39Z

OK, this PR should be good at this point! (Tempting fate by saying this before CI has completed...)

skrap · 2022-01-20T16:14:35Z

The CI failures seem independent of these changes. Perhaps it's a new clippy lint?

rtzoeller · 2022-01-20T16:15:38Z

The CI failures seem independent of these changes. Perhaps it's a new clippy lint?

Was just responding about that. I'll investigate and fix it independently of this PR, and will try to look at this in the next day or two.

README.md

src/sys/signal.rs

src/sys/socket/addr.rs

test/test_fcntl.rs

test/sys/mod.rs

test/test_fcntl.rs

skrap · 2022-01-24T15:07:34Z

rebased on master to resolve conflicted Cargo.toml file.

rtzoeller · 2022-01-25T03:37:28Z

bors r+

bors · 2022-01-25T03:52:10Z

skrap · 2022-01-28T14:27:05Z

Thanks for the review and the merge!

rtzoeller added this to the 0.24.0 milestone Dec 10, 2021

asomers reviewed Dec 11, 2021

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skrap mentioned this pull request Dec 14, 2021

uclibc: fix type of EXTPROC. rust-lang/libc#2592

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rtzoeller mentioned this pull request Dec 21, 2021

Remove broken newlib support #1571

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skrap mentioned this pull request Jan 19, 2022

uclibc: fix O_TMPFILE value, hide some unused fields to fix libc-test rust-lang/libc#2636

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skrap force-pushed the master branch from e037053 to 2f5278f Compare January 20, 2022 03:36

skrap force-pushed the master branch 2 times, most recently from 134dd22 to 91e8eb3 Compare January 20, 2022 15:59

rtzoeller reviewed Jan 21, 2022

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skrap force-pushed the master branch from 91e8eb3 to d69e2ed Compare January 21, 2022 13:55

asomers reviewed Jan 21, 2022

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skrap force-pushed the master branch from d69e2ed to 5c9c54f Compare January 22, 2022 01:16

uclibc support

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skrap force-pushed the master branch from 5c9c54f to 6c4b913 Compare January 24, 2022 15:06

bors bot merged commit 5cd01a1 into nix-rust:master Jan 25, 2022

lancethepants mentioned this pull request Feb 1, 2022

Add new target armv7-unknown-linux-uclibceabi (softfloat) rust-lang/rust#92383

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rtzoeller mentioned this pull request Feb 5, 2022

Add accept4 on DragonFly, Emscripten, Fuchsia, Illumos, and NetBSD. #1654

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rtzoeller mentioned this pull request Apr 24, 2022

add haiku support #1703

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zhangwenlong8911 mentioned this pull request Jun 13, 2022

Add support for loongarch64 #1738

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uclibc support #1603

uclibc support #1603

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uclibc support #1603

uclibc support #1603

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