Separate L4Re from Linux code, add aarch64 and enable tests #4479

farao · 2025-06-09T17:11:05Z

The L4Re code was previously attached to the Linux code which was not correct in many ways. This commit separates the L4Re code and enables the libc-tests and includes the fixes for the failing tests. Aarch64 is added as a second supported architecture (more to come).

Sources

L4Re-adapted version of uclibc: https://github.com/kernkonzept/l4re-core/tree/master/uclibc/lib.

Checklist

Relevant tests in libc-test/semver have been updated
No placeholder or unstable values like *LAST or *MAX are
included (see #3131)
Tested locally (cd libc-test && cargo test --target mytarget);
especially relevant for platforms that may not be checked in CI

rustbot · 2025-06-09T17:11:12Z

Some changes occurred in the Android module

cc @maurer

farao · 2025-06-13T08:50:10Z

Hi @tgross35, this is the refactoring of the recent L4Re PR: #4383 (which is kept around just in case).

I think the failure of the freebsd nightly checks is not my fault. The rest succeeds now.

I did most of what you requested in your comment on the old PR, I just kept the linux/mod.rs file around since there is a massive part of code that is linux-only and is not supported by L4Re and it did not seem to make sense to put it all in shared.rs.

Also, I put some more code that's shared from the sub modules (emscripten, android, linux, l4re) up in linux_like/mod.rs. In theory, I think there's potential to do that with more code, that's just the one that I would have put in shared.rs but realized that it could go into linux_like/mod.rs instead.

tgross35

Sorry this has taken a while to get to, but thank you for all the changes here! The shape of this one looks much better. I have a handful of small comments but will need to take a deeper look at the big refactor portions again.

ci/run-docker.sh

libc-test/build.rs

src/unix/linux_like/l4re/uclibc/mod.rs

src/unix/linux_like/l4re/uclibc/x86_64/mod.rs

src/unix/linux_like/shared.rs

tgross35 · 2025-07-07T17:20:28Z

@rustbot author, for the above review and a rebase

rustbot · 2025-07-07T17:20:33Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rustbot · 2025-11-20T10:02:43Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

farao · 2025-11-20T12:40:10Z

@rustbot ready

src/unix/linux_like/linux/gnu/mod.rs

src/unix/linux_like/linux/mod.rs

src/unix/linux_like/linux_l4re_shared.rs

src/unix/linux_like/linux/mod.rs

src/unix/linux_like/linux_l4re_shared.rs

src/unix/linux_like/linux/mod.rs

tgross35 · 2025-11-20T14:29:39Z

src/unix/linux_like/l4re/mod.rs

+use crate::prelude::*;
+
+pub type l4_umword_t = c_ulong; // Unsigned machine word.
+pub type pthread_t = *mut c_void;


Where does this come from? From https://github.com/search?q=repo%3Akernkonzept%2Fl4re-core+%2Ftypedef.*pthread_t%3B%2F&type=code, it seems like they are all c_ulong, like upstream uclibc. (Not that it really matters too much.)

I will try to investigate (since changing it brings me a warning). I'd like to leave it for another PR if that's ok.

tgross35 · 2025-11-20T14:32:42Z

src/unix/linux_like/l4re/uclibc/mod.rs

+    #[cfg_attr(any(target_pointer_width = "32",), repr(align(4)))]
+    #[cfg_attr(not(any(target_pointer_width = "32",)), repr(align(8)))]
+    pub struct pthread_mutexattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_MUTEXATTR_T],
+    }
+
+    #[cfg_attr(any(target_pointer_width = "32"), repr(align(4)))]
+    #[cfg_attr(all(target_pointer_width = "64"), repr(align(8)))]
+    pub struct pthread_rwlockattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_RWLOCKATTR_T],
+    }
+
+    #[repr(align(4))]
+    pub struct pthread_condattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_CONDATTR_T],
+    }
+
+    #[repr(align(4))]
+    pub struct pthread_barrierattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_BARRIERATTR_T],
+    }


I'm looking at the definitions here https://github.com/kernkonzept/l4re-core/blob/e1bf5beeb2933af404b03ca1571e82f33c3385c2/libc/uclibc-ng/libpthread/include/bits/pthreadtypes.h and they don't seem to match up at all - is that the wrong place?

No, the definitions are different. I thought it might have been a concious design decision in the linux part of the code to commonize the pthread structs by just putting an array of bytes into them so I kept this (especially because some time in the near future we might support other libcs). But I'm also happy to choose the actual struct definitions if you prefer this?

Oh no it wasn't a deviant decision, that's actually how they're defined in the linux libs https://github.com/bminor/glibc/blob/f9e61cd446d45016e20b6fe85ab87364ebdbec1b/sysdeps/nptl/bits/pthreadtypes.h#L67-L72. I would indeed prefer to match the struct definitions (with all fields private). It's much easier to make sure the fields line up than to add manually compute the size/align, and I don't know that the sizes are likely to always stay the same across platforms anyway.

The L4Re code was previously attached to the Linux code which was not correct in many ways. This commit separates the L4Re code and enables the libc-tests and includes the fixes for the failing tests. Aarch64 is added as a second supported architecture (more to come).

farao · 2025-11-21T08:49:56Z

@rustbot ready

tgross35

Still some leftovers in the pthread definitions, and I would like the uclibc pthread defs to match source rather than using the array. But after this, LGTM!

tgross35 · 2025-11-30T06:45:23Z

src/unix/linux_like/l4re/uclibc/mod.rs

+    #[cfg_attr(any(target_pointer_width = "32",), repr(align(4)))]
+    #[cfg_attr(not(any(target_pointer_width = "32",)), repr(align(8)))]
+    pub struct pthread_mutexattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_MUTEXATTR_T],
+    }
+
+    #[cfg_attr(any(target_pointer_width = "32"), repr(align(4)))]
+    #[cfg_attr(all(target_pointer_width = "64"), repr(align(8)))]
+    pub struct pthread_rwlockattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_RWLOCKATTR_T],
+    }
+
+    #[repr(align(4))]
+    pub struct pthread_condattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_CONDATTR_T],
+    }
+
+    #[repr(align(4))]
+    pub struct pthread_barrierattr_t {
+        #[doc(hidden)]
+        size: [u8; crate::__SIZEOF_PTHREAD_BARRIERATTR_T],
+    }


Oh no it wasn't a deviant decision, that's actually how they're defined in the linux libs https://github.com/bminor/glibc/blob/f9e61cd446d45016e20b6fe85ab87364ebdbec1b/sysdeps/nptl/bits/pthreadtypes.h#L67-L72. I would indeed prefer to match the struct definitions (with all fields private). It's much easier to make sure the fields line up than to add manually compute the size/align, and I don't know that the sizes are likely to always stay the same across platforms anyway.

tgross35 · 2025-11-30T06:58:09Z

src/unix/linux_like/linux/mod.rs

-        size: [u8; crate::__SIZEOF_PTHREAD_COND_T],
+        pub size: [u8; crate::__SIZEOF_PTHREAD_COND_T],


tgross35 · 2025-11-30T06:58:39Z

src/unix/linux_like/linux/mod.rs

    #[cfg_attr(
        all(
-            any(target_env = "musl", target_env = "ohos"),
+            any(target_env = "musl", target_env = "ohos", target_os = "emscripten"),
            target_pointer_width = "32"
        ),
        repr(align(4))
    )]
    #[cfg_attr(
        all(
-            any(target_env = "musl", target_env = "ohos"),
+            any(target_env = "musl", target_env = "ohos", target_os = "emscripten"),
            target_pointer_width = "64"
        ),
        repr(align(8))
    )]
    #[cfg_attr(
        all(
-            not(any(target_env = "musl", target_env = "ohos")),
+            not(any(target_env = "musl", target_env = "ohos", target_os = "emscripten")),
            target_arch = "x86"
        ),
        repr(align(4))
    )]
    #[cfg_attr(
        all(
-            not(any(target_env = "musl", target_env = "ohos")),
+            not(any(target_env = "musl", target_env = "ohos", target_os = "emscripten")),
            not(target_arch = "x86")
        ),
        repr(align(8))
    )]
    pub struct pthread_cond_t {


Could you please make sure to self-review these pthread diffs? Again this has some changes for emscripten that aren't relevant.

tgross35 · 2025-11-30T06:59:29Z

src/unix/linux_like/linux/mod.rs

                target_arch = "powerpc",
                target_arch = "sparc",
                target_arch = "x86_64",
-                target_arch = "x86"
+                target_arch = "x86",
+                target_os = "emscripten",
            )
        ),
        repr(align(4))


Ditto, drop this

tgross35 · 2025-11-30T06:59:35Z

src/unix/linux_like/linux/mod.rs

                target_arch = "powerpc",
                target_arch = "sparc",
                target_arch = "x86_64",
-                target_arch = "x86"
+                target_arch = "x86",
+                target_os = "emscripten",
            ))
        ),
        repr(align(8))
    )]
    pub struct pthread_mutex_t {
        #[doc(hidden)]
-        size: [u8; crate::__SIZEOF_PTHREAD_MUTEX_T],
+        pub size: [c_char; crate::__SIZEOF_PTHREAD_MUTEX_T],
    }

    #[cfg_attr(
        all(
            target_pointer_width = "32",
            any(
+                target_os = "emscripten",
                target_arch = "mips",
                target_arch = "mips32r6",
                target_arch = "arm",


tgross35 · 2025-11-30T06:59:43Z

src/unix/linux_like/linux/mod.rs

        any(
            target_pointer_width = "64",
            not(any(
+                target_os = "emscripten",
                target_arch = "mips",
                target_arch = "mips32r6",
                target_arch = "arm",


tgross35 · 2025-11-30T06:59:49Z

src/unix/linux_like/linux/mod.rs

        repr(align(8))
    )]
    pub struct pthread_rwlock_t {
-        size: [u8; crate::__SIZEOF_PTHREAD_RWLOCK_T],
+        pub size: [u8; crate::__SIZEOF_PTHREAD_RWLOCK_T],
    }

    #[cfg_attr(


This is imperfect but should get things closer to what is available on l4re's uclibc fork. Based on work by Marius Melzer [rust-lang#4479]. [rust-lang#4479]: rust-lang#4479 (backport <rust-lang#4836>) (cherry picked from commit 34d8ce7)

This is imperfect but should get things closer to what is available on l4re's uclibc fork. Based on work by Marius Melzer [#4479]. [#4479]: #4479 (backport <#4836>) (cherry picked from commit 34d8ce7)

rustbot added ctest Issues relating to the ctest crate O-android O-gnu O-linux O-linux-like O-musl O-unix O-x86 S-waiting-on-review labels Jun 9, 2025

farao force-pushed the revert branch 11 times, most recently from 92284e5 to 40a082a Compare June 12, 2025 16:33

farao mentioned this pull request Jun 13, 2025

Separate L4Re code, add aarch64 and enable tests #4383

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farao force-pushed the revert branch 2 times, most recently from 26e9993 to 5b60e70 Compare June 23, 2025 09:15

tgross35 reviewed Jun 26, 2025

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farao force-pushed the revert branch from f438c6d to b79f672 Compare November 20, 2025 10:02

farao force-pushed the revert branch 5 times, most recently from 61f844b to b64b370 Compare November 20, 2025 12:39

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farao added 3 commits November 20, 2025 21:52

Add uclibc aarch64 support for L4Re

22072f1

l4re: pthread fixes in new

53cd7c0

farao force-pushed the revert branch from b64b370 to cc783d1 Compare November 20, 2025 20:53

linux_like: communize some structs

58263db

farao force-pushed the revert branch from cc783d1 to 58263db Compare November 21, 2025 08:34

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maurer approved these changes Nov 24, 2025

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rustbot added S-waiting-on-author and removed S-waiting-on-review labels Nov 30, 2025

		size: [u8; crate::__SIZEOF_PTHREAD_COND_T],
		pub size: [u8; crate::__SIZEOF_PTHREAD_COND_T],

Separate L4Re from Linux code, add aarch64 and enable tests #4479

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Separate L4Re from Linux code, add aarch64 and enable tests #4479

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farao commented Jun 9, 2025

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