std: add platform support for hexagon-unknown-qurt by androm3da · Pull Request #152084 · rust-lang/rust

androm3da · 2026-02-04T04:50:05Z

QuRT is not a unix target but provides POSIX-compatible threading, file I/O, and synchronization APIs. This implementation does not declare unix as a target family. Instead, it explicitly opts into the unix PAL and selects unix-based implementations for individual subsystems where QuRT's POSIX layer is sufficient.

Supported: alloc, threading, mutex, condvar, rwlock, once, thread parking, TLS, file system, file descriptors, stdio, I/O slices, I/O errors, is_terminal, env, paths, time, exit, personality/unwinding, backtrace

Stubbed; returns Err: process spawning, networking, pipes, hostname
Stubbed; returns empty: command-line args
Stubbed; panics: random

Platform modules:

New os::qurt module with platform-specific extensions (ffi, fs, io, raw)

rustbot · 2026-02-04T04:50:10Z

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androm3da · 2026-02-04T15:14:47Z

This PR depends on a newer version of the libc crate - maybe I'll let this PR hang here for a bit and check back in when it gets released and promoted?

joboet · 2026-02-07T15:21:04Z

This PR depends on a newer version of the libc crate - maybe I'll let this PR hang here for a bit and check back in when it gets released and promoted?

You need libc at 0.2.179, right? You can update libc here – but please keep it in a separate commit.

joboet · 2026-02-07T15:35:05Z

@rustbot author

rustbot · 2026-02-07T15:35:10Z

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

androm3da · 2026-02-08T18:25:04Z

This PR depends on a newer version of the libc crate - maybe I'll let this PR hang here for a bit and check back in when it gets released and promoted?

You need libc at 0.2.179, right? You can update libc here – but please keep it in a separate commit.

The commit I need - rust-lang/libc@9934c04 is not yet tagged/released. Or rather there is a ctest-* tag but I suspect that doesn't apply/not intended use for that tag. Should I try to execute a tag/release of libc, or just wait for that to happen naturally?

androm3da · 2026-02-17T06:16:27Z

This PR depends on a newer version of the libc crate - maybe I'll let this PR hang here for a bit and check back in when it gets released and promoted?

You need libc at 0.2.179, right? You can update libc here – but please keep it in a separate commit.

The commit I need - rust-lang/libc@9934c04 is not yet tagged/released. Or rather there is a ctest-* tag but I suspect that doesn't apply/not intended use for that tag. Should I try to execute a tag/release of libc, or just wait for that to happen naturally?

Ah - I see now that it appears in 0.2.181 and there's already a PR open for that (#150752). I'll rebase when that lands.

androm3da · 2026-04-14T14:20:46Z

LGTM once libc::stat and raw::stat match

Fixed

quic-mliebel · 2026-04-16T16:40:20Z

Looks like blkcnt_t and blksize_t are needed:

python3 x.py check library --target hexagon-unknown-qurt

...

error[E0432]: unresolved import `super::platform::raw::blkcnt_t`
  --> library/std/src/os/unix/raw.rs:30:32
   |
30 | pub use super::platform::raw::{blkcnt_t, time_t};
   |                                ^^^^^^^^ no `blkcnt_t` in `os::qurt::raw`
   |
   = help: consider importing this type alias instead:
           libc::blkcnt_t

error[E0432]: unresolved import `super::platform::raw::blksize_t`
  --> library/std/src/os/unix/raw.rs:33:32
   |
33 | pub use super::platform::raw::{blksize_t, dev_t, ino_t, mode_t, nlink_t, off_t};
   |                                ^^^^^^^^^ no `blksize_t` in `os::qurt::raw`
   |
   = help: consider importing this type alias instead:
           libc::blksize_t

androm3da · 2026-04-16T23:24:31Z

Looks like blkcnt_t and blksize_t are needed:

python3 x.py check library --target hexagon-unknown-qurt

...

error[E0432]: unresolved import `super::platform::raw::blkcnt_t`
  --> library/std/src/os/unix/raw.rs:30:32
   |
30 | pub use super::platform::raw::{blkcnt_t, time_t};
   |                                ^^^^^^^^ no `blkcnt_t` in `os::qurt::raw`
   |
   = help: consider importing this type alias instead:
           libc::blkcnt_t

error[E0432]: unresolved import `super::platform::raw::blksize_t`
  --> library/std/src/os/unix/raw.rs:33:32
   |
33 | pub use super::platform::raw::{blksize_t, dev_t, ino_t, mode_t, nlink_t, off_t};
   |                                ^^^^^^^^^ no `blksize_t` in `os::qurt::raw`
   |
   = help: consider importing this type alias instead:
           libc::blksize_t

Fixed, thanks

androm3da · 2026-05-04T19:14:29Z

ping @joboet

joboet · 2026-05-05T16:18:34Z

Sorry for the delay, I was taking a bit of a break from reviewing.

Could you provide a bit more context on QuRT? It looks like quite a lot of UNIX stuff is stubbed out here. How much UNIX-compatibility does QuRT actually provide? I'm asking because we have some similar UNIX-adjacent targets (e.g. Hermit, TEEOS) that don't list UNIX as their target family and instead just reuse the UNIX code in std where applicable.

@rustbot label +I-libs-nominated
I think this question has come up before, but how much UNIX-compatibility do you want to require for the UNIX target family?

androm3da · 2026-05-05T17:34:07Z

Sorry for the delay, I was taking a bit of a break from reviewing.

Could you provide a bit more context on QuRT? It looks like quite a lot of UNIX stuff is stubbed out here. How much UNIX-compatibility does QuRT actually provide? I'm asking because we have some similar UNIX-adjacent targets (e.g. Hermit, TEEOS) that don't list UNIX as their target family and instead just reuse the UNIX code in std where applicable.

QuRT is a proprietary RTOS for Hexagon, ARM, RISC-V architectures that is usually focused on embedded DSP/uC devices without a direct storage device, without an interactive terminal/shell/UART. It has memory-protected processes, some POSIX capability like pthreads/mutexes. QuRT lacks SysV IPC. QuRT provides an indirect access to a filesystem via calls to some-other-SoC-node-with-a-disk.

But yeah - I'm totally fine w/redoing this PR to avoid touching UNIX and making it look more like hermit/teeos. Will take a look and update the PR.

rustbot · 2026-05-06T01:43:39Z

Some changes occurred in src/doc/rustc/src/platform-support

cc @Noratrieb

These commits modify compiler targets.
(See the Target Tier Policy.)

rustbot · 2026-05-06T01:43:41Z

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.

the8472 · 2026-05-06T16:41:32Z

Platform modules:
* New os::qurt module with platform-specific extensions to ffi, fs, io, raw

* QuRT-specific file handling for ino, dev, mode, nlink, etc.
Unsupported: Networking, fork/exec, pipe, chown/fchown/lchown/chroot/mkfifo

Can you provide some more details? By expanding the "etc.". For example time and randomness aren't covered by your list.
And want to know which APIs are stubbed in a way that results in panics vs. those that return Err results.

androm3da · 2026-05-06T17:41:32Z

Can you provide some more details? By expanding the "etc.". For example time and randomness aren't covered by your list. And want to know which APIs are stubbed in a way that results in panics vs. those that return Err results.

I've updated the PR description like so:

Supported: alloc, threading, mutex, condvar, rwlock, once, thread parking, TLS, file system, file descriptors, stdio, I/O slices, I/O errors, is_terminal, env, paths, time, exit, personality/unwinding, backtrace

Stubbed; returns Err: process spawning, networking, pipes, hostname
Stubbed; returns empty: command-line args
Stubbed; panics: random

nia-e · 2026-05-13T16:30:37Z

@@ -114,7 +114,7 @@ pub(crate) fn get_result_from_exit_code(
        Some(TR_OK) => TestResult::TrOk,
        #[cfg(windows)]
        Some(STATUS_FAIL_FAST_EXCEPTION) => TestResult::TrFailed,
-        #[cfg(unix)]
+        #[cfg(all(unix, not(target_os = "qurt")))]


So, is qurt unix or not for cfg purposes? This seems to not be consistent throughout the PR

View changes since the review

Sorry, I'll make it consistent.

joshtriplett · 2026-05-13T16:33:19Z

@@ -1,6 +1,11 @@
 #![forbid(unsafe_op_in_unsafe_fn)]

 cfg_select! {
+    // QuRT uses unsupported pipes since it doesn't support process spawning
+    target_os = "qurt" => {


This is no longer needed since qurt is no longer unix.

View changes since the review

Fixed, thanks

nia-e · 2026-05-13T16:35:23Z

The conclusion from today's libs meeting was that this target is (given what we're seeing) Not Unix, but properly defining what is unix is best left for a refactor of the cfgs we expose

Remove unix family from hexagon-unknown-qurt target spec and instead explicitly opt into unix implementations where applicable, following the pattern used by similar unix-adjacent targets. The target uses the unix PAL and explicitly selects unix implementations for the supported features. Modules that remain unsupported for qurt: process spawning, networking and pipes.

Update documentation with details about how to leverage qurt, now that there's some level of libstd support

joboet

@rust-lang/libs-api how do you feel about the API additions here? Adding an instant-deprecated stat definitions seems a bit weird to me.

View changes since this review

joboet · 2026-05-21T13:56:38Z

+- **`thread::yield_now()`**: Calls `sched_yield` which is stubbed to `abort`;
+  use `thread::sleep(Duration::from_millis(0))` as an alternative


Couldn't std do that? yield_now aborting seems bad, even having it be a noop is better.

joboet · 2026-05-21T13:57:59Z

@@ -227,6 +231,7 @@ impl<'a> AsRawFd for io::StdinLock<'a> {
 }

 #[stable(feature = "asraw_stdio_locks", since = "1.35.0")]
+#[cfg(not(target_os = "qurt"))]


But stdio is supported, right? Why wouldn't this be available?

joboet · 2026-05-21T13:59:32Z

This isn't used anymore, right? If so, then could you remove this change please?

joboet · 2026-05-21T14:03:49Z

@@ -3,6 +3,10 @@ use crate::fmt;

 pub struct Args {}

+pub unsafe fn init(_argc: isize, _argv: *const *const u8) {


This should be gated for QuRT, otherwise other unsupported targets will complain about the unused function.

joboet · 2026-05-21T14:07:05Z

@@ -124,6 +129,7 @@ pub fn set_permissions(path: &Path, perm: FilePermissions) -> io::Result<()> {
 pub fn set_permissions_nofollow(path: &Path, perm: crate::fs::Permissions) -> io::Result<()> {
    use crate::fs::OpenOptions;

+    #[cfg_attr(any(target_os = "espidf", target_os = "horizon"), allow(unused_mut))]


Thanks! I suggest #[expect] instead of #[allow], it means we'll notice if the attribute becomes unnecessary.

joboet · 2026-05-21T14:12:04Z

Please undo this change, this is no longer needed.

joboet · 2026-05-21T14:14:52Z

Insert the config here instead of adding a manual fallback.

joboet · 2026-05-21T14:15:00Z

+#[cfg(target_os = "qurt")]
+pub fn set_name(_name: &CStr) {
+    // QuRT doesn't support pthread_setname_np
+}
+


Suggested change

#[cfg(target_os = "qurt")]

pub fn set_name(_name: &CStr) {

// QuRT doesn't support pthread_setname_np

}

joboet · 2026-05-21T14:21:41Z

+    -C "link-args=${QURTLIB}/crt1.o ${HEXLIB}/crt0.o ${HEXLIB}/init.o ${QURTLIB}/debugmon.o" \
+    -C "link-args=-Wl,--section-start=.start=0x40000" \
+    -C "link-args=-Wl,--defsym=sched_yield=abort" \
+    -C "link-args=-Wl,--defsym=unsetenv=abort" \


Making remove_env panic seems like a much nicer way of handling this.

joboet · 2026-05-21T14:22:55Z

@@ -31,9 +31,9 @@ cfg_select! {
        unix,
        windows,
        target_os = "psp",
+        target_os = "qurt",


You might be able to get rid of the weird symbol redefinitions by not linking to them here and just aborting in panic_unwind instead.

There are a number of other targets that don't support unwinding either, I suggest you have a look at the Hermit implementation in particular.

rustbot assigned joboet Feb 4, 2026

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androm3da force-pushed the bcain/qurt-libstd-support branch from 791d71f to 3201966 Compare February 4, 2026 15:11

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androm3da mentioned this pull request Feb 4, 2026

x.py build --stage 1 library/std --target hexagon-unknown-qurt fails: libunwind requires link.h; std then fails due to missing libc/platform items #151212

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androm3da added 2 commits May 13, 2026 14:34

Update hexagon-unknown-qurt platform support documentation

091e154

Update documentation with details about how to leverage qurt, now that there's some level of libstd support

androm3da force-pushed the bcain/qurt-libstd-support branch from 2db6d1f to 091e154 Compare May 13, 2026 21:39

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 21, 2026

		- `thread::yield_now()`: Calls `sched_yield` which is stubbed to `abort`;
		use `thread::sleep(Duration::from_millis(0))` as an alternative

		@@ -3,6 +3,10 @@ use crate::fmt;

		pub struct Args {}

		pub unsafe fn init(_argc: isize, _argv: const const u8) {

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androm3da commented Apr 14, 2026

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androm3da commented Feb 4, 2026 •

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