Promote armv7a-none-eabihf to Tier 2 #146522

thejpster · 2025-09-13T19:26:03Z

This PR promotes armv7a-none-eabihf to Tier 2, to join armv7r-none-eabihf and armv7a-none-eabi. I believe it was simply an oversight that it wasn't made Tier 2 before, as most Armv7-A targets have an FPU and it often makes sense to use it.

This PR wil be rebased once #146419 completes the queue.

A tier 2 target must have value to people other than its maintainers. (It may
still be a niche target, but it must not be exclusively useful for an
inherently closed group.)

The armv7a-none-eabihf target is for all Arm Cortex-A processors (either 32-bit only, or in 32-bit mode) where the user wants to use the FPU.

A tier 2 target must have a designated team of developers (the "target
maintainers") available to consult on target-specific build-breaking issues,
or if necessary to develop target-specific language or library implementation
details. This team must have at least 2 developers.

The Embedded Devices Working Group's Arm Team have just started maintaining this target.

The target must not place undue burden on Rust developers not specifically
concerned with that target. Rust developers are expected to not gratuitously
break a tier 2 target, but are not expected to become experts in every tier 2
target, and are not expected to provide target-specific implementations for
every tier 2 target.

This target is highly similar to a number of existing Tier 2 targets, including armv7r-none-eabihf and armv7a-none-eabi and so it should not add undue burden.

The target must provide documentation for the Rust community explaining how
to build for the target using cross-compilation, and explaining how to run
tests for the target. If at all possible, this documentation should show how
to run Rust programs and tests for the target using emulation, to allow
anyone to do so. If the target cannot be feasibly emulated, the documentation
should explain how to obtain and work with physical hardware, cloud systems,
or equivalent.

https://doc.rust-lang.org/nightly/rustc/platform-support/armv7a-none-eabi.html was added in #146419. It covers the -eabi and the -eabihf targets.

The target must document its baseline expectations for the features or
versions of CPUs, operating systems, libraries, runtime environments, and
similar.

I believe it does.

If introducing a new tier 2 or higher target that is identical to an existing
Rust target except for the baseline expectations for the features or versions
of CPUs, operating systems, libraries, runtime environments, and similar,
then the proposed target must document to the satisfaction of the approving
teams why the specific difference in baseline expectations provides
sufficient value to justify a separate target.

It uses very similar FPUs to armv7r-none-eabihf but is otherwise the same as armv7a-none-eabi.

Tier 2 targets must not leave any significant portions of core or the
standard library unimplemented or stubbed out, unless they cannot possibly be
supported on the target.

It has a full libcore, as per the other arm*-none-* targets.

The code generation backend for the target should not have deficiencies that
invalidate Rust safety properties, as evaluated by the Rust compiler team.

It should be the same backend as armv7r-none-eabihf and friends, except for FPU support, which is already covered in thumbv8m.main-none-eabihf. There are no issues that I know of.

If the target supports C code, and the target has an interoperable calling
convention for C code, the Rust target must support that C calling convention
for the platform via extern "C". The C calling convention does not need to
be the default Rust calling convention for the target, however.

The ABI is EABI, the same as many other Arm targets.

The target must build reliably in CI, for all components that Rust's CI
considers mandatory.

The https://github.com/rust-embedded/cortex-ar repository has been changed in rust-embedded/cortex-ar#57 to build this target with -Zbuild-std=core. Locally it seems fine.

The approving teams may additionally require that a subset of tests pass in
CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may
apply if the target builds host tools, or if the tests in question provide
substantial value via early detection of critical problems.

There are no no-std tests in the tree that I'm aware of.

Building the target in CI must not take substantially longer than the current
slowest target in CI, and should not substantially raise the maintenance
burden of the CI infrastructure. This requirement is subjective, to be
evaluated by the infrastructure team, and will take the community importance
of the target into account.

Building libcore is quite fast.

Tier 2 targets should, if at all possible, support cross-compiling. Tier 2
targets should not require using the target as the host for builds, even if
the target supports host tools.

It does.

In addition to the legal requirements for all targets (specified in the tier
3 requirements), because a tier 2 target typically involves the Rust project
building and supplying various compiled binaries, incorporating the target
and redistributing any resulting compiled binaries (e.g. built libraries,
host tools if any) must not impose any onerous license requirements on any
members of the Rust project, including infrastructure team members and those
operating CI systems. This is a subjective requirement, to be evaluated by
the approving teams.

Just libcore required (and liballoc). No known issues here.

Tier 2 targets must not impose burden on the authors of pull requests, or
other developers in the community, to ensure that tests pass for the target.

Noted

The target maintainers should regularly run the testsuite for the target

The https://github.com/rust-embedded/cortex-ar repository will be changed to use the rustup component when available.

and should fix any test failures in a reasonably timely fashion.

Noted

rustbot · 2025-09-13T19:26:06Z

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

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

cc @Noratrieb

rustbot · 2025-09-13T19:26:08Z

r? @petrochenkov

rustbot has assigned @petrochenkov.
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

This is the target for 32-bit Cortex-A bare-metal, when using the FPU. The target is well tested by the Embedded Devices Working Group, and the soft-float target (armv7a-none-eabi) is already Tier 2.

rustbot · 2025-09-14T08:52:06Z

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.

thejpster · 2025-09-14T08:53:04Z

Rebased now #146419 is in.

petrochenkov · 2025-09-24T16:43:38Z

Blocked on rust-lang/compiler-team#913.
@rustbot blocked

… r=jackh726 Demote both armebv7r-none-* targets. OK, slightly more controversial than rust-lang#146520 and rust-lang#146522 - I'd like to drop the bare-metal **big-endian** Armv7-R targets down to Tier 3. The reason is simple - we cannot test them in https://github.com/rust-embedded/cortex-ar/. This because QEMU support for Big Endian Armv7-R is broken. I tried quite hard, but all the strings I printed with semihosting came out byte swapped (or "etybawa depp") because of how QEMU kludges the access to memory in big-endian mode. The target also has only a single maintainer. Although, if `@chrisnc` wants to put up a case for keeping it at Tier 2 though, I'm happy to hear it! This PR wil be rebased once rust-lang#146419 completes the queue.

… r=jackh726 Demote both armebv7r-none-* targets. OK, slightly more controversial than rust-lang#146520 and rust-lang#146522 - I'd like to drop the bare-metal **big-endian** Armv7-R targets down to Tier 3. The reason is simple - we cannot test them in https://github.com/rust-embedded/cortex-ar/. This because QEMU support for Big Endian Armv7-R is broken. I tried quite hard, but all the strings I printed with semihosting came out byte swapped (or "etybawa depp") because of how QEMU kludges the access to memory in big-endian mode. The target also has only a single maintainer. Although, if ``@chrisnc`` wants to put up a case for keeping it at Tier 2 though, I'm happy to hear it! This PR wil be rebased once rust-lang#146419 completes the queue.

… r=jackh726 Demote both armebv7r-none-* targets. OK, slightly more controversial than rust-lang#146520 and rust-lang#146522 - I'd like to drop the bare-metal **big-endian** Armv7-R targets down to Tier 3. The reason is simple - we cannot test them in https://github.com/rust-embedded/cortex-ar/. This because QEMU support for Big Endian Armv7-R is broken. I tried quite hard, but all the strings I printed with semihosting came out byte swapped (or "etybawa depp") because of how QEMU kludges the access to memory in big-endian mode. The target also has only a single maintainer. Although, if ```@chrisnc``` wants to put up a case for keeping it at Tier 2 though, I'm happy to hear it! This PR wil be rebased once rust-lang#146419 completes the queue.

… r=jackh726 Demote both armebv7r-none-* targets. OK, slightly more controversial than rust-lang#146520 and rust-lang#146522 - I'd like to drop the bare-metal **big-endian** Armv7-R targets down to Tier 3. The reason is simple - we cannot test them in https://github.com/rust-embedded/cortex-ar/. This because QEMU support for Big Endian Armv7-R is broken. I tried quite hard, but all the strings I printed with semihosting came out byte swapped (or "etybawa depp") because of how QEMU kludges the access to memory in big-endian mode. The target also has only a single maintainer. Although, if ````@chrisnc```` wants to put up a case for keeping it at Tier 2 though, I'm happy to hear it! This PR wil be rebased once rust-lang#146419 completes the queue.

Rollup merge of #146523 - thejpster:demote-armebv7r-targets, r=jackh726 Demote both armebv7r-none-* targets. OK, slightly more controversial than #146520 and #146522 - I'd like to drop the bare-metal **big-endian** Armv7-R targets down to Tier 3. The reason is simple - we cannot test them in https://github.com/rust-embedded/cortex-ar/. This because QEMU support for Big Endian Armv7-R is broken. I tried quite hard, but all the strings I printed with semihosting came out byte swapped (or "etybawa depp") because of how QEMU kludges the access to memory in big-endian mode. The target also has only a single maintainer. Although, if ````@chrisnc```` wants to put up a case for keeping it at Tier 2 though, I'm happy to hear it! This PR wil be rebased once #146419 completes the queue.

Demote both armebv7r-none-* targets. OK, slightly more controversial than rust-lang/rust#146520 and rust-lang/rust#146522 - I'd like to drop the bare-metal **big-endian** Armv7-R targets down to Tier 3. The reason is simple - we cannot test them in https://github.com/rust-embedded/cortex-ar/. This because QEMU support for Big Endian Armv7-R is broken. I tried quite hard, but all the strings I printed with semihosting came out byte swapped (or "etybawa depp") because of how QEMU kludges the access to memory in big-endian mode. The target also has only a single maintainer. Although, if ````@chrisnc```` wants to put up a case for keeping it at Tier 2 though, I'm happy to hear it! This PR wil be rebased once rust-lang/rust#146419 completes the queue.

thejpster · 2025-10-10T14:21:19Z

The FCP is complete

petrochenkov · 2025-10-10T14:34:13Z

@bors r+

bors · 2025-10-10T14:34:16Z

📌 Commit 215c936 has been approved by petrochenkov

It is now in the queue for this repository.

Rollup of 12 pull requests Successful merges: - #145651 (Regression test for const promotion with Option<Ordering>) - #145722 (implement Extend<{Group, Literal, Punct, Ident}> for TokenStream) - #146520 (Promote armv8r-none-eabihf target to Tier 2) - #146522 (Promote armv7a-none-eabihf to Tier 2) - #147289 (Mitigate `thread_local!` shadowing issues) - #147515 (Update rustc-perf submodule) - #147522 (compiletest: Use the same directive lines for EarlyProps and ignore/only/needs) - #147525 (Replace locals in debuginfo records during ref_prop and dest_prop) - #147544 (Remove StatementKind::Deinit.) - #147551 (remove `#[rustc_inherit_overflow_checks]` from `is_multiple_of`) - #147553 (Move `wasm32-wasip3` to the tier 3 table) - #147562 (Stabilize `NonZero<u*>::div_ceil`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #146522 - thejpster:promote-armv7a-none-eabihf, r=petrochenkov Promote armv7a-none-eabihf to Tier 2 This PR promotes armv7a-none-eabihf to Tier 2, to join armv7r-none-eabihf and armv7a-none-eabi. I believe it was simply an oversight that it wasn't made Tier 2 before, as most Armv7-A targets have an FPU and it often makes sense to use it. This PR wil be rebased once #146419 completes the queue. > - A tier 2 target must have value to people other than its maintainers. (It may > still be a niche target, but it must not be exclusively useful for an > inherently closed group.) The `armv7a-none-eabihf` target is for all Arm Cortex-A processors (either 32-bit only, or in 32-bit mode) where the user wants to use the FPU. >- A tier 2 target must have a designated team of developers (the "target > maintainers") available to consult on target-specific build-breaking issues, > or if necessary to develop target-specific language or library implementation > details. This team must have at least 2 developers. The Embedded Devices Working Group's Arm Team have just started maintaining this target. > - The target must not place undue burden on Rust developers not specifically > concerned with that target. Rust developers are expected to not gratuitously > break a tier 2 target, but are not expected to become experts in every tier 2 > target, and are not expected to provide target-specific implementations for > every tier 2 target. This target is highly similar to a number of existing Tier 2 targets, including `armv7r-none-eabihf` and `armv7a-none-eabi` and so it should not add undue burden. > - The target must provide documentation for the Rust community explaining how > to build for the target using cross-compilation, and explaining how to run > tests for the target. If at all possible, this documentation should show how > to run Rust programs and tests for the target using emulation, to allow > anyone to do so. If the target cannot be feasibly emulated, the documentation > should explain how to obtain and work with physical hardware, cloud systems, > or equivalent. https://doc.rust-lang.org/nightly/rustc/platform-support/armv7a-none-eabi.html was added in #146419. It covers the `-eabi` and the `-eabihf` targets. > - The target must document its baseline expectations for the features or > versions of CPUs, operating systems, libraries, runtime environments, and > similar. I believe it does. > - If introducing a new tier 2 or higher target that is identical to an existing > Rust target except for the baseline expectations for the features or versions > of CPUs, operating systems, libraries, runtime environments, and similar, > then the proposed target must document to the satisfaction of the approving > teams why the specific difference in baseline expectations provides > sufficient value to justify a separate target. It uses very similar FPUs to `armv7r-none-eabihf` but is otherwise the same as `armv7a-none-eabi`. > - Tier 2 targets must not leave any significant portions of `core` or the > standard library unimplemented or stubbed out, unless they cannot possibly be > supported on the target. It has a full libcore, as per the other arm*-none-* targets. > - The code generation backend for the target should not have deficiencies that > invalidate Rust safety properties, as evaluated by the Rust compiler team. It should be the same backend as `armv7r-none-eabihf` and friends, except for FPU support, which is already covered in `thumbv8m.main-none-eabihf`. There are no issues that I know of. > - If the target supports C code, and the target has an interoperable calling > convention for C code, the Rust target must support that C calling convention > for the platform via `extern "C"`. The C calling convention does not need to > be the default Rust calling convention for the target, however. The ABI is EABI, the same as many other Arm targets. > - The target must build reliably in CI, for all components that Rust's CI > considers mandatory. The https://github.com/rust-embedded/cortex-ar repository has been changed in rust-embedded/cortex-ar#57 to build this target with `-Zbuild-std=core`. Locally it seems fine. > - The approving teams may additionally require that a subset of tests pass in > CI, such as enough to build a functional "hello world" program, `./x.py test > --no-run`, or equivalent "smoke tests". In particular, this requirement may > apply if the target builds host tools, or if the tests in question provide > substantial value via early detection of critical problems. There are no no-std tests in the tree that I'm aware of. > - Building the target in CI must not take substantially longer than the current > slowest target in CI, and should not substantially raise the maintenance > burden of the CI infrastructure. This requirement is subjective, to be > evaluated by the infrastructure team, and will take the community importance > of the target into account. Building libcore is quite fast. > - Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 > targets should not require using the target as the host for builds, even if > the target supports host tools. It does. > - In addition to the legal requirements for all targets (specified in the tier > 3 requirements), because a tier 2 target typically involves the Rust project > building and supplying various compiled binaries, incorporating the target > and redistributing any resulting compiled binaries (e.g. built libraries, > host tools if any) must not impose any onerous license requirements on any > members of the Rust project, including infrastructure team members and those > operating CI systems. This is a subjective requirement, to be evaluated by > the approving teams. Just libcore required (and liballoc). No known issues here. > - Tier 2 targets must not impose burden on the authors of pull requests, or > other developers in the community, to ensure that tests pass for the target. Noted > - The target maintainers should regularly run the testsuite for the target The https://github.com/rust-embedded/cortex-ar repository will be changed to use the rustup component when available. > and should fix any test failures in a reasonably timely fashion. Noted

* Adds armv7a-none-eabihf (rust-lang#146522) * Adds armv8r-none-eabihf (rust-lang#146520) * Drops armeb*-none-* (rust-lang#146523)

…ets, r=Mark-Simulacrum Adjust the Arm targets in CI to reflect latest changes * Adds build of `armv7a-none-eabihf` (rust-lang#146522) * Adds build of `armv8r-none-eabihf` (rust-lang#146520) * Drops build of `armeb*-none-*` (rust-lang#146523) I wasn't sure why `armv7a-none-eabihf` was missing from the build-manifest program, but `armv8r-none-eabihf` was there, as they were both Tier 3 targets up until very recently. So, I added it, but that might be wrong.

Rollup of 12 pull requests Successful merges: - rust-lang/rust#145651 (Regression test for const promotion with Option<Ordering>) - rust-lang/rust#145722 (implement Extend<{Group, Literal, Punct, Ident}> for TokenStream) - rust-lang/rust#146520 (Promote armv8r-none-eabihf target to Tier 2) - rust-lang/rust#146522 (Promote armv7a-none-eabihf to Tier 2) - rust-lang/rust#147289 (Mitigate `thread_local!` shadowing issues) - rust-lang/rust#147515 (Update rustc-perf submodule) - rust-lang/rust#147522 (compiletest: Use the same directive lines for EarlyProps and ignore/only/needs) - rust-lang/rust#147525 (Replace locals in debuginfo records during ref_prop and dest_prop) - rust-lang/rust#147544 (Remove StatementKind::Deinit.) - rust-lang/rust#147551 (remove `#[rustc_inherit_overflow_checks]` from `is_multiple_of`) - rust-lang/rust#147553 (Move `wasm32-wasip3` to the tier 3 table) - rust-lang/rust#147562 (Stabilize `NonZero<u*>::div_ceil`) r? `@ghost` `@rustbot` modify labels: rollup

…ets, r=Mark-Simulacrum Adjust the Arm targets in CI to reflect latest changes * Adds build of `armv7a-none-eabihf` (rust-lang#146522) * Adds build of `armv8r-none-eabihf` (rust-lang#146520) * Drops build of `armeb*-none-*` (rust-lang#146523) I wasn't sure why `armv7a-none-eabihf` was missing from the build-manifest program, but `armv8r-none-eabihf` was there, as they were both Tier 3 targets up until very recently. So, I added it, but that might be wrong.

Rollup merge of #147596 - thejpster:build-new-arm-tier2-targets, r=Mark-Simulacrum Adjust the Arm targets in CI to reflect latest changes * Adds build of `armv7a-none-eabihf` (#146522) * Adds build of `armv8r-none-eabihf` (#146520) * Drops build of `armeb*-none-*` (#146523) I wasn't sure why `armv7a-none-eabihf` was missing from the build-manifest program, but `armv8r-none-eabihf` was there, as they were both Tier 3 targets up until very recently. So, I added it, but that might be wrong.

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 13, 2025

rustbot assigned petrochenkov Sep 13, 2025

thejpster mentioned this pull request Sep 13, 2025

Demote both armebv7r-none-* targets. #146523

Merged

Promote armv7a-none-eabihf to Tier 2

215c936

This is the target for 32-bit Cortex-A bare-metal, when using the FPU. The target is well tested by the Embedded Devices Working Group, and the soft-float target (armv7a-none-eabi) is already Tier 2.

thejpster force-pushed the promote-armv7a-none-eabihf branch from 6234c2d to 215c936 Compare September 14, 2025 08:52

thejpster mentioned this pull request Sep 14, 2025

Promote armv7a-none-eabihf to Tier 2 rust-lang/compiler-team#913

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3 tasks

rustbot added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 24, 2025

petrochenkov added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-blocked Status: Blocked on something else such as an RFC or other implementation work. labels Oct 10, 2025

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 Oct 10, 2025

dianqk mentioned this pull request Oct 10, 2025

Rollup of 12 pull requests #147574

Merged

bors merged commit e1af13b into rust-lang:master Oct 11, 2025
10 checks passed

rustbot added this to the 1.92.0 milestone Oct 11, 2025

thejpster deleted the promote-armv7a-none-eabihf branch October 11, 2025 16:58

thejpster mentioned this pull request Oct 11, 2025

Adjust the Arm targets in CI to reflect latest changes #147596

Merged

Zalathar pushed a commit to Zalathar/rust that referenced this pull request Oct 12, 2025

Adjust the Arm targets in CI to reflect latest changes

cc96d3f

* Adds armv7a-none-eabihf (rust-lang#146522) * Adds armv8r-none-eabihf (rust-lang#146520) * Drops armeb*-none-* (rust-lang#146523)

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