Add `std` support for `armv7a-vex-v5` #145973

Tropix126 · 2025-08-28T22:13:29Z

This PR adds standard library support for the VEX V5 Brain (armv7a-vex-v5 target). It is more-or-less an updated version of the library-side work done in #131530.

This was a joint effort between me, @lewisfm, @max-niederman, @Gavin-Niederman and several other members of the vexide project.

Background

VEXos is a fairly unconventional operating system, with user code running in a restricted enviornment with regards to I/O capabilities and whatnot. As such, several OS-dependent APIs are unsupported or have partial support (such as std::net, std::process, and most of std::thread). A more comprehensive list of what does or doesn't work is outlined in the updated target documentation. Despite these limitations, we believe that libstd support on this target still has value to users, especially given the popular use of this hardware for educational purposes. For some previous discussion on this matter, see this comment.

SDK Linkage

VEXos doesn't really ship with an official libc or POSIX-style platform API (and though it does port newlib, these are stubbed on top of the underlying SDK). Instead, VEX provides their own SDK for calling platform APIs. Their official SDK is kept proprietary (with public headers), though open-source implementations exist. Following the precedent of the armv6k-nintendo-3ds team's work in #95897, we've opted not to directly link libstd to any SDK with the expectation that users will provide their own with one of the following options:

vex-sdk-download, which downloads an official proprietary SDK from VEX using a build script.
vex-sdk-jumptable, which is a compatible, open-source reimplementation of the SDK using firmware jumps.
vex-sdk-pros, which uses the PROS kernel as a provider for SDK functions.
Linking their own implementation or stubbing the functions required by libstd.

The vex-sdk crate used in the VEXos PAL provides libc-style FFI bindings for any compatible system library, so any of these options should work fine. A functional demo project using vex-sdk-download can be found here.

Future Work

This PR implements virtually everything we are currently able to implement given the current capabilities of the platform. The exception to this is file directory enumeration, though the implementation of that is sufficiently gross enough to drive us away from supporting this officially.

Additionally, I have a working branch implementing the panic_unwind runtime for this target, which is something that would be nice to see in the future, though given the volume of compiler changes i've deemed it out-of-scope for this PR.

rustbot · 2025-08-28T22:13:34Z

r? @tgross35

rustbot has assigned @tgross35.
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 · 2025-08-28T22:13:38Z

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

cc @Noratrieb

These commits modify the library/Cargo.lock file. Unintentional changes to library/Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

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

The list of allowed third-party dependencies may have been modified! You must ensure that any new dependencies have compatible licenses before merging.

cc @davidtwco, @wesleywiser

library/std/src/sys/alloc/vexos.rs

library/std/src/sys/fs/vexos.rs

tgross35 · 2025-08-28T22:53:46Z

I think the limitations here seem fine, and from a quick skim nothing jumps out to me as problematic. Nominating to make sure the team doesn't have any concerns.

@rustbot label +I-libs-nominated

library/std/Cargo.toml

library/std/src/sys/alloc/vexos.rs

library/std/src/sys/fs/vexos.rs

library/std/src/sys/pal/vexos/mod.rs

library/std/src/sys/pal/vexos/time.rs

tgross35 · 2025-08-30T01:14:52Z

@rustbot author

rustbot · 2025-08-30T01:14:55Z

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

Tropix126 · 2025-08-30T02:47:53Z

@rustbot ready

tgross35 · 2025-08-30T03:00:48Z

Thanks for the updates here, I'll take a more thorough look through after the libs meeting (next Wednesday).

bors · 2025-09-03T18:49:56Z

☔ The latest upstream changes (presumably #146160) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot · 2025-09-05T23:02:10Z

Some changes occurred in src/tools/cargo

cc @ehuss

library/std/src/sys/fs/vexos.rs

rustbot · 2025-09-20T23:16:22Z

This PR was rebased onto a different master 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.

library/std/src/sys/stdio/vexos.rs

library/std/src/sys/fs/vexos.rs

Tropix126 · 2025-09-23T22:00:00Z

Think all of the review concerns are addressed. Going to run some hardware tests to make sure nothing regressed anyways (mainly around File::seek and Stdin).

@rustbot ready

Tropix126 · 2025-09-23T22:15:53Z

Hardware tests seem fine.

tgross35

Updates look great! Noticed one last nit on error messages.

Please squash, r=me after that and the error message change

View changes since this review

library/std/src/sys/fs/vexos.rs

Tropix126 · 2025-09-24T15:34:38Z

Done! Think things are in order (don't think I have permissions for bors r=). @tgross35

tgross35 · 2025-09-24T16:31:35Z

Code changes look good to me! But on a history nit, for the squashed commit it looks like you aren't listed as the author. Since you prepared the final state, you probably want to git commit --amend --reset-author to set youself as the author, then add @lewisfm back as a co-author (via Co-authored-by: Name <email> at the end of the commit message https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/creating-a-commit-with-multiple-authors).

Also you don't really need to keep all the squashed messages in the final commit message since they aren't relevant anymore. I know this is the default behavior for rebase s/squash, but by squash we really tend to mean f/fixup 🙂

Co-authored-by: Lewis McClelland <[email protected]>

Tropix126 · 2025-09-24T17:13:47Z

Code changes look good to me! But on a history nit, for the squashed commit it looks like you aren't listed as the author.

Yeah, I squashed everything into the first commit, which is why it ended up that way. I've fixed that issue and added lewis back as a co-author.

tgross35 · 2025-09-24T17:44:58Z

Looks great! Thanks for all the work here.

@bors r+

bors · 2025-09-24T17:45:01Z

📌 Commit b2634e3 has been approved by tgross35

It is now in the queue for this repository.

Add `std` support for `armv7a-vex-v5` This PR adds standard library support for the VEX V5 Brain (`armv7a-vex-v5` target). It is more-or-less an updated version of the library-side work done in rust-lang#131530. This was a joint effort between me, ``@lewisfm,`` ``@max-niederman,`` ``@Gavin-Niederman`` and several other members of the [`vexide` project](https://github.com/vexide/). ## Background VEXos is a fairly unconventional operating system, with user code running in a restricted enviornment with regards to I/O capabilities and whatnot. As such, several OS-dependent APIs are unsupported or have partial support (such as `std::net`, `std::process`, and most of `std::thread`). A more comprehensive list of what does or doesn't work is outlined in the [updated target documentation](https://github.com/vexide/rust/blob/vex-std/src/doc/rustc/src/platform-support/armv7a-vex-v5.md). Despite these limitations, we believe that `libstd` support on this target still has value to users, especially given the popular use of this hardware for educational purposes. For some previous discussion on this matter, see [this comment](rust-lang#131530 (comment)). ## SDK Linkage VEXos doesn't really ship with an official `libc` or POSIX-style platform API (and though it does port newlib, these are stubbed on top of the underlying SDK). Instead, VEX provides their own SDK for calling platform APIs. Their official SDK is kept proprietary (with public headers), though open-source implementations exist. Following the precedent of the `armv6k-nintendo-3ds` team's work in rust-lang#95897, we've opted not to directly link `libstd` to any SDK with the expectation that users will provide their own with one of the following options: - [`vex-sdk-download`](https://github.com/vexide/vex-sdk/tree/main/packages/vex-sdk-download), which downloads an official proprietary SDK from VEX using a build script. - [`vex-sdk-jumptable`](https://crates.io/crates/vex-sdk-jumptable), which is a compatible, open-source reimplementation of the SDK using firmware jumps. - [`vex-sdk-pros`](https://github.com/vexide/vex-sdk/tree/main/packages/vex-sdk-pros), which uses the [PROS kernel](https://github.com/purduesigbots/pros) as a provider for SDK functions. - Linking their own implementation or stubbing the functions required by libstd. The `vex-sdk` crate used in the VEXos PAL provides `libc`-style FFI bindings for any compatible system library, so any of these options *should* work fine. A functional demo project using `vex-sdk-download` can be found [here](https://github.com/vexide/armv7a-vex-v5-demo/tree/main). ## Future Work This PR implements virtually everything we are currently able to implement given the current capabilities of the platform. The exception to this is file directory enumeration, though the implementation of that is sufficiently [gross enough](https://github.com/vexide/vexide/blob/c6c5bad11e035cf4e51d429dca7e427210185ed4/packages/vexide-core/src/fs/mod.rs#L987) to drive us away from supporting this officially. Additionally, I have a working branch implementing the `panic_unwind` runtime for this target, which is something that would be nice to see in the future, though given the volume of compiler changes i've deemed it out-of-scope for this PR.

Rollup of 14 pull requests Successful merges: - #145067 (RawVecInner: add missing `unsafe` to unsafe fns) - #145277 (Do not materialise X in [X; 0] when X is unsizing a const) - #145973 (Add `std` support for `armv7a-vex-v5`) - #146667 (Add an attribute to check the number of lanes in a SIMD vector after monomorphization) - #146735 (unstably constify float mul_add methods) - #146737 (f16_f128: enable some more tests in Miri) - #146766 (Add attributes for #[global_allocator] functions) - #146905 (llvm: update remarks support on LLVM 22) - #146982 (Remove erroneous normalization step in `tests/run-make/linker-warning`) - #147005 (Small string formatting cleanup) - #147007 (Explicitly note `&[SocketAddr]` impl of `ToSocketAddrs`) - #147008 (bootstrap.py: Respect build.jobs while building bootstrap tool) - #147013 (rustdoc: Fix documentation for `--doctest-build-arg`) - #147015 (Use `LLVMDisposeTargetMachine`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #145973 - vexide:vex-std, r=tgross35 Add `std` support for `armv7a-vex-v5` This PR adds standard library support for the VEX V5 Brain (`armv7a-vex-v5` target). It is more-or-less an updated version of the library-side work done in #131530. This was a joint effort between me, `@lewisfm,` `@max-niederman,` `@Gavin-Niederman` and several other members of the [`vexide` project](https://github.com/vexide/). ## Background VEXos is a fairly unconventional operating system, with user code running in a restricted enviornment with regards to I/O capabilities and whatnot. As such, several OS-dependent APIs are unsupported or have partial support (such as `std::net`, `std::process`, and most of `std::thread`). A more comprehensive list of what does or doesn't work is outlined in the [updated target documentation](https://github.com/vexide/rust/blob/vex-std/src/doc/rustc/src/platform-support/armv7a-vex-v5.md). Despite these limitations, we believe that `libstd` support on this target still has value to users, especially given the popular use of this hardware for educational purposes. For some previous discussion on this matter, see [this comment](#131530 (comment)). ## SDK Linkage VEXos doesn't really ship with an official `libc` or POSIX-style platform API (and though it does port newlib, these are stubbed on top of the underlying SDK). Instead, VEX provides their own SDK for calling platform APIs. Their official SDK is kept proprietary (with public headers), though open-source implementations exist. Following the precedent of the `armv6k-nintendo-3ds` team's work in #95897, we've opted not to directly link `libstd` to any SDK with the expectation that users will provide their own with one of the following options: - [`vex-sdk-download`](https://github.com/vexide/vex-sdk/tree/main/packages/vex-sdk-download), which downloads an official proprietary SDK from VEX using a build script. - [`vex-sdk-jumptable`](https://crates.io/crates/vex-sdk-jumptable), which is a compatible, open-source reimplementation of the SDK using firmware jumps. - [`vex-sdk-pros`](https://github.com/vexide/vex-sdk/tree/main/packages/vex-sdk-pros), which uses the [PROS kernel](https://github.com/purduesigbots/pros) as a provider for SDK functions. - Linking their own implementation or stubbing the functions required by libstd. The `vex-sdk` crate used in the VEXos PAL provides `libc`-style FFI bindings for any compatible system library, so any of these options *should* work fine. A functional demo project using `vex-sdk-download` can be found [here](https://github.com/vexide/armv7a-vex-v5-demo/tree/main). ## Future Work This PR implements virtually everything we are currently able to implement given the current capabilities of the platform. The exception to this is file directory enumeration, though the implementation of that is sufficiently [gross enough](https://github.com/vexide/vexide/blob/c6c5bad11e035cf4e51d429dca7e427210185ed4/packages/vexide-core/src/fs/mod.rs#L987) to drive us away from supporting this officially. Additionally, I have a working branch implementing the `panic_unwind` runtime for this target, which is something that would be nice to see in the future, though given the volume of compiler changes i've deemed it out-of-scope for this PR.

rustbot assigned tgross35 Aug 28, 2025

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Tropix126 force-pushed the vex-std branch from 3288184 to 09ab298 Compare September 3, 2025 20:37

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Tropix126 mentioned this pull request Sep 14, 2025

feat: std-compatible vexide vexide/vexide#361

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Tropix126 force-pushed the vex-std branch from 8ad25ac to d7717f8 Compare September 24, 2025 15:27

std: add support for armv7a-vex-v5 target

b2634e3

Co-authored-by: Lewis McClelland <[email protected]>

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Zalathar mentioned this pull request Sep 25, 2025

Rollup of 14 pull requests #147019

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Rollup of 8 pull requests #147020

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bors merged commit 0a34928 into rust-lang:master Sep 25, 2025
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std: fix warning in VEXos stdio module #147049

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Add std support for armv7a-vex-v5 #145973

Add std support for armv7a-vex-v5 #145973

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Add `std` support for `armv7a-vex-v5` #145973

Add `std` support for `armv7a-vex-v5` #145973

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