Add libstd support for Trusty targets #136842

randomPoison · 2025-02-11T00:38:04Z

This PR adds support for alloc and std for the Trusty targets based on the internal patches used in Android. The original patches can be seen here and here. Please let me know if there's any additional context I need to add.

rustbot · 2025-02-11T00:38:14Z

r? @ChrisDenton

rustbot has assigned @ChrisDenton.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

rustbot · 2025-02-11T00:38:16Z

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

cc @Noratrieb

joboet · 2025-02-11T12:33:53Z

library/std/src/sys/thread_local/mod.rs

Why not use the static-backed TLS implementation (the one also used by UEFI)?

We haven't tested against that implementation yet, unfortunately. We made these patches when before the static TLS implementation was added (I think, I'm not entirely sure when that was added), so we've been using our own.

The static-based implementation is very old, as it is used on WASM without atomics as well. Would it be possible for you to try switching to it? For one, it would reduce the amount of code that has to be maintained in std. And this would fix the unsoundness mentioned in my other comment.

ChrisDenton · 2025-02-14T14:11:49Z

I'm concerned with how much is stubbed out. So far it seems like this only allows writing to stdout and provides an entropy source?

Is there any possibility that more things may be implemented in the future? E.g. Instant (and perhaps other time related items).

randomPoison · 2025-02-14T19:41:15Z

A lot ends up being stubbed out because Trusty userspace is pretty limited in terms of what you can do: No filesystem access, no threads, can't spawn processes, no network sockets, etc. We still make use of a good chunk of std though, so it's been worthwhile for us to add Trusty support to libstd.

I do think we'll want to add Instant and other time-related things, we just haven't gotten around to that yet. I'm not sure what other parts of std we'll want to add support for in the future, but I can look into it more if that'd be helpful here.

ChrisDenton · 2025-02-14T23:07:35Z

Ok, I've nominated this for the libs team to discuss. While tier 3 libstd targets have a lot of latitude, there is some expectation that they should have or be working towards some basic level of libstd support. My concern would be that Trusty is fundamentally too limited for that and should remain no_std plus alloc. However, I'm not certain so I'll defer to the team's decision.

workingjubilee · 2025-02-17T08:48:18Z

library/std/src/os/fd/raw.rs

@@ -207,6 +214,7 @@ impl AsRawFd for io::Stderr {
 }

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


Adding a bunch of cfg seems like a tacit admission that this implementation is not very useful, and depends on certain implementations never being even referenced.

In general, we have avoided adding cfg to the implementations of std. I do not think we should get in the habit here.

Is there a better approach to follow for disabling unsupported parts of std? Would it be better to instead stub out platform APIs with unimplemented!? That would involve fewer cfgs, though I'm not sure how to handle tests with that approach.

There is really no satisfactory answer, to be clear, which is why we have shifted towards being increasingly reluctant to allow targets to add only partial support for std.

m-ou-se · 2025-02-19T17:27:38Z

Ok, I've nominated this for the libs team to discuss. While tier 3 libstd targets have a lot of latitude, there is some expectation that they should have or be working towards some basic level of libstd support. My concern would be that Trusty is fundamentally too limited for that and should remain no_std plus alloc. However, I'm not certain so I'll defer to the team's decision.

We discussed this in the libs meeting just now. Given that a few more things will likely be added (Instant, etc.), we're okay with moving forward with this as a tier 3 target.

joboet · 2025-02-19T17:43:20Z

library/std/src/sys/thread_local/mod.rs

The static-based implementation is very old, as it is used on WASM without atomics as well. Would it be possible for you to try switching to it? For one, it would reduce the amount of code that has to be maintained in std. And this would fix the unsoundness mentioned in my other comment.

library/std/src/sys/thread_local/key/trusty.rs

joboet · 2025-02-19T18:06:39Z

library/std/src/os/mod.rs

@@ -178,7 +180,7 @@ pub mod vxworks;
 #[cfg(target_os = "xous")]
 pub mod xous;

-#[cfg(any(unix, target_os = "hermit", target_os = "wasi", doc))]
+#[cfg(any(unix, target_os = "hermit", target_os = "trusty", target_os = "wasi", doc))]


This whole module is about providing safe abstractions for file descriptors that maintain IO safety. But if I understand the documentation correctly, there is no way to open or close file descriptors on Trusty, meaning the whole concept of IO safety is unnecessary. Thus I don't think that this module should exist on Trusty.

We do make heavy use of OwnedFd in Trusty. While userspace applications can't directly open e.g. a file, we do have a concept of handles that are used for things like IPC. We'd also like to have access to the os::fd module because Trusty shares code with Android, and it'd be difficult if we had two different fd types. Sharing the same fd infrastructure in libstd simplifies things for us a lot.

randomPoison · 2025-02-19T20:12:14Z

The static-based implementation is very old, as it is used on WASM without atomics as well. Would it be possible for you to try switching to it?

@joboet Fair point, I've wanted to switch us to the common static TLS implementation anyway. That's done now.

ChrisDenton

I'm broadly ok with this now but it will need a rebase to take account of the reorganisational of the standard library. E.g. library/std/src/sys/fs/.

Unclear why this needs to be done manually and is not done by the existing Trusty patches.

randomPoison · 2025-03-10T21:22:49Z

I have rebased the changes and updated them to account for the latest libstd reorganization.

ChrisDenton · 2025-03-11T13:28:14Z

Ok, I'm still a bit hesitant about a number of the #[cfg(not(target_os = "trusty"))] and I do suspect there's a better way to do organise this but I won't block this PR on figuring that out.

@bors r+

bors · 2025-03-11T13:28:17Z

📌 Commit 2b3b0bd has been approved by ChrisDenton

It is now in the queue for this repository.

library/std/build.rs

ChrisDenton · 2025-03-11T14:06:58Z

@bors r-

Co-authored-by: bjorn3 <[email protected]>

ChrisDenton · 2025-03-12T02:16:33Z

@bors r+

bors · 2025-03-12T02:16:36Z

📌 Commit d3c55cd has been approved by ChrisDenton

It is now in the queue for this repository.

…hrisDenton Add libstd support for Trusty targets This PR adds support for `alloc` and `std` for the Trusty targets based on the internal patches used in Android. The original patches can be seen [here](https://android.googlesource.com/toolchain/android_rust/+/refs/heads/main/patches/development/rustc-0023-Add-Trusty-OS-support-to-Rust-std.patch) and [here](https://android.googlesource.com/toolchain/android_rust/+/refs/heads/main/patches/development/rustc-0054-Add-std-os-fd-support-for-Trusty.patch). Please let me know if there's any additional context I need to add.

Rollup of 25 pull requests Successful merges: - rust-lang#134076 (Stabilize `std::io::ErrorKind::InvalidFilename`) - rust-lang#136842 (Add libstd support for Trusty targets) - rust-lang#137314 (change definitely unproductive cycles to error) - rust-lang#137504 (Move methods from Map to TyCtxt, part 4.) - rust-lang#137621 (Add std support to cygwin target) - rust-lang#137701 (Convert `ShardedHashMap` to use `hashbrown::HashTable`) - rust-lang#138109 (make precise capturing args in rustdoc Json typed) - rust-lang#138161 (Add PeekMut::refresh) - rust-lang#138162 (Update the standard library to Rust 2024) - rust-lang#138174 (Elaborate trait assumption in `receiver_is_dispatchable`) - rust-lang#138175 (Support rmeta inputs for --crate-type=bin --emit=obj) - rust-lang#138269 (uefi: fs: Implement FileType, FilePermissions and FileAttr) - rust-lang#138313 (Update books) - rust-lang#138318 (Rustdoc: remove a bunch of `@ts-expect-error` from main.js) - rust-lang#138331 (Use `RUSTC_LINT_FLAGS` more) - rust-lang#138333 (Rebuild llvm spuriously less frequently) - rust-lang#138343 (Enable `f16` tests for `powf`) - rust-lang#138345 (Some autodiff cleanups) - rust-lang#138346 (naked functions: on windows emit `.endef` without the symbol name) - rust-lang#138347 (Reduce `kw::Empty` usage, part 2) - rust-lang#138360 (Fix false-positive in `expr_or_init` and in the `invalid_from_utf8` lint) - rust-lang#138371 (Update compiletest's `has_asm_support` to match rustc) - rust-lang#138372 (Refactor `pick2_mut` & `pick3_mut` to use `get_disjoint_mut`) - rust-lang#138376 (Item-related cleanups) - rust-lang#138377 (Remove unnecessary lifetime from `PatInfo`.) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned ChrisDenton Feb 11, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Feb 11, 2025

joboet requested changes Feb 11, 2025

View reviewed changes

ChrisDenton added the I-libs-nominated Nominated for discussion during a libs team meeting. label Feb 14, 2025

workingjubilee reviewed Feb 17, 2025

View reviewed changes

m-ou-se removed the I-libs-nominated Nominated for discussion during a libs team meeting. label Feb 19, 2025

joboet requested changes Feb 19, 2025

View reviewed changes

ChrisDenton reviewed Mar 10, 2025

View reviewed changes

randomPoison and others added 8 commits March 10, 2025 10:00

Apply rustc-0023-Add-Trusty-OS-support-to-Rust-std.patch

87ca2db

Apply rustc-0054-Add-std-os-fd-support-for-Trusty.patch

7f6ee12

Format after patches have been applied

d633d8e

Disable unsupported tests

22fea97

Unclear why this needs to be done manually and is not done by the existing Trusty patches.

Update Trusty platform docs

5b94113

Remove custom TLS implementation for Trusty targets

0b1a7ab

Update Trusty support to account for recent libstd reorganization

f5dd3d1

Remove unused file

2b3b0bd

randomPoison force-pushed the trusty-libstd-v3 branch from 34ca6c0 to 2b3b0bd Compare March 10, 2025 21:20

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 11, 2025

bjorn3 reviewed Mar 11, 2025

View reviewed changes

library/std/build.rs Outdated Show resolved Hide resolved

bors 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Mar 11, 2025

Remove unnecessary parens

d3c55cd

Co-authored-by: bjorn3 <[email protected]>

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 12, 2025

jieyouxu mentioned this pull request Mar 12, 2025

Rollup of 26 pull requests #138382

Closed

jieyouxu mentioned this pull request Mar 12, 2025

Rollup of 25 pull requests #138383

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Add libstd support for Trusty targets #136842

Add libstd support for Trusty targets #136842

randomPoison commented Feb 11, 2025

rustbot commented Feb 11, 2025

rustbot commented Feb 11, 2025

joboet Feb 11, 2025

randomPoison Feb 11, 2025

joboet Feb 19, 2025

ChrisDenton commented Feb 14, 2025

randomPoison commented Feb 14, 2025

ChrisDenton commented Feb 14, 2025

workingjubilee Feb 17, 2025

randomPoison Feb 17, 2025

workingjubilee Feb 18, 2025

m-ou-se commented Feb 19, 2025

joboet Feb 19, 2025

joboet Feb 19, 2025

randomPoison Feb 19, 2025

randomPoison commented Feb 19, 2025

ChrisDenton left a comment

randomPoison commented Mar 10, 2025

ChrisDenton commented Mar 11, 2025 •

edited

Loading

bors commented Mar 11, 2025

ChrisDenton commented Mar 11, 2025

ChrisDenton commented Mar 12, 2025

bors commented Mar 12, 2025

Add libstd support for Trusty targets #136842

Are you sure you want to change the base?

Add libstd support for Trusty targets #136842

Conversation

randomPoison commented Feb 11, 2025

rustbot commented Feb 11, 2025

rustbot commented Feb 11, 2025

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

ChrisDenton commented Feb 14, 2025

randomPoison commented Feb 14, 2025

ChrisDenton commented Feb 14, 2025

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

m-ou-se commented Feb 19, 2025

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

randomPoison commented Feb 19, 2025

ChrisDenton left a comment

Choose a reason for hiding this comment

randomPoison commented Mar 10, 2025

ChrisDenton commented Mar 11, 2025 • edited Loading

bors commented Mar 11, 2025

ChrisDenton commented Mar 11, 2025

ChrisDenton commented Mar 12, 2025

bors commented Mar 12, 2025

ChrisDenton commented Mar 11, 2025 •

edited

Loading