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Auto merge of #114004 - hermitcore:riscv64gc-unknown-hermit, r=davidtwco
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Add `riscv64gc-unknown-hermit` target

This PR adds the new `riscv64gc-unknown-hermit` target, initially created by `@simonschoening,` a 64-bit RISC-V target for the [Hermit] unikernel project.

Furthermore, this cleans up the existing Hermit targets and adds a platform support documentation page for _all_ Hermit targets and goes through the new tier 3 target policy process:

[Hermit]: https://github.com/hermitcore

## Tier 3 target policy

> - A tier 3 target must have a designated developer or developers (the "target
>   maintainers") on record to be CCed when issues arise regarding the target.
>   (The mechanism to track and CC such developers may evolve over time.)

`@stlankes` as the Hermit project lead and I will be the target maintainers.

> - Targets must use naming consistent with any existing targets; for instance, a
>   target for the same CPU or OS as an existing Rust target should use the same
>   name for that CPU or OS. Targets should normally use the same names and
>   naming conventions as used elsewhere in the broader ecosystem beyond Rust
>   (such as in other toolchains), unless they have a very good reason to
>   diverge. Changing the name of a target can be highly disruptive, especially
>   once the target reaches a higher tier, so getting the name right is important
>   even for a tier 3 target.
>   - Target names should not introduce undue confusion or ambiguity unless
>     absolutely necessary to maintain ecosystem compatibility. For example, if
>     the name of the target makes people extremely likely to form incorrect
>     beliefs about what it targets, the name should be changed or augmented to
>     disambiguate it.
>   - If possible, use only letters, numbers, dashes and underscores for the name.
>     Periods (`.`) are known to cause issues in Cargo.

The target name `riscv64gc-unknown-hermit` was derived from the existing `x86_64-unknown-hermit` and `aarch64-unknown-hermit` targets.

> - Tier 3 targets may have unusual requirements to build or use, but must not
>   create legal issues or impose onerous legal terms for the Rust project or for
>   Rust developers or users.
>   - The target must not introduce license incompatibilities.
>   - Anything added to the Rust repository must be under the standard Rust
>     license (`MIT OR Apache-2.0`).
>   - The target must not cause the Rust tools or libraries built for any other
>     host (even when supporting cross-compilation to the target) to depend
>     on any new dependency less permissive than the Rust licensing policy. This
>     applies whether the dependency is a Rust crate that would require adding
>     new license exceptions (as specified by the `tidy` tool in the
>     rust-lang/rust repository), or whether the dependency is a native library
>     or binary. In other words, the introduction of the target must not cause a
>     user installing or running a version of Rust or the Rust tools to be
>     subject to any new license requirements.
>   - Compiling, linking, and emitting functional binaries, libraries, or other
>     code for the target (whether hosted on the target itself or cross-compiling
>     from another target) must not depend on proprietary (non-FOSS) libraries.
>     Host tools built for the target itself may depend on the ordinary runtime
>     libraries supplied by the platform and commonly used by other applications
>     built for the target, but those libraries must not be required for code
>     generation for the target; cross-compilation to the target must not require
>     such libraries at all. For instance, `rustc` built for the target may
>     depend on a common proprietary C runtime library or console output library,
>     but must not depend on a proprietary code generation library or code
>     optimization library. Rust's license permits such combinations, but the
>     Rust project has no interest in maintaining such combinations within the
>     scope of Rust itself, even at tier 3.
>   - "onerous" here is an intentionally subjective term. At a minimum, "onerous"
>     legal/licensing terms include but are *not* limited to: non-disclosure
>     requirements, non-compete requirements, contributor license agreements
>     (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms,
>     requirements conditional on the employer or employment of any particular
>     Rust developers, revocable terms, any requirements that create liability
>     for the Rust project or its developers or users, or any requirements that
>     adversely affect the livelihood or prospects of the Rust project or its
>     developers or users.

No dependencies were added to Rust.

> - Neither this policy nor any decisions made regarding targets shall create any
>   binding agreement or estoppel by any party. If any member of an approving
>   Rust team serves as one of the maintainers of a target, or has any legal or
>   employment requirement (explicit or implicit) that might affect their
>   decisions regarding a target, they must recuse themselves from any approval
>   decisions regarding the target's tier status, though they may otherwise
>   participate in discussions.
>   - This requirement does not prevent part or all of this policy from being
>     cited in an explicit contract or work agreement (e.g. to implement or
>     maintain support for a target). This requirement exists to ensure that a
>     developer or team responsible for reviewing and approving a target does not
>     face any legal threats or obligations that would prevent them from freely
>     exercising their judgment in such approval, even if such judgment involves
>     subjective matters or goes beyond the letter of these requirements.

Understood.
I am not a member of a Rust team.

> - Tier 3 targets should attempt to implement as much of the standard libraries
>   as possible and appropriate (`core` for most targets, `alloc` for targets
>   that can support dynamic memory allocation, `std` for targets with an
>   operating system or equivalent layer of system-provided functionality), but
>   may leave some code unimplemented (either unavailable or stubbed out as
>   appropriate), whether because the target makes it impossible to implement or
>   challenging to implement. The authors of pull requests are not obligated to
>   avoid calling any portions of the standard library on the basis of a tier 3
>   target not implementing those portions.

Understood.
`std` is supported.

> - The target must provide documentation for the Rust community explaining how
>   to build for the target, using cross-compilation if possible. If the target
>   supports running binaries, or running tests (even if they do not pass), the
>   documentation must explain how to run such binaries or tests for the target,
>   using emulation if possible or dedicated hardware if necessary.

Building is described in the platform support doc.

> - Tier 3 targets must not impose burden on the authors of pull requests, or
>   other developers in the community, to maintain the target. In particular,
>   do not post comments (automated or manual) on a PR that derail or suggest a
>   block on the PR based on a tier 3 target. Do not send automated messages or
>   notifications (via any medium, including via ``@`)` to a PR author or others
>   involved with a PR regarding a tier 3 target, unless they have opted into
>   such messages.
>   - Backlinks such as those generated by the issue/PR tracker when linking to
>     an issue or PR are not considered a violation of this policy, within
>     reason. However, such messages (even on a separate repository) must not
>     generate notifications to anyone involved with a PR who has not requested
>     such notifications.

Understood.

> - Patches adding or updating tier 3 targets must not break any existing tier 2
>   or tier 1 target, and must not knowingly break another tier 3 target without
>   approval of either the compiler team or the maintainers of the other tier 3
>   target.
>   - In particular, this may come up when working on closely related targets,
>     such as variations of the same architecture with different features. Avoid
>     introducing unconditional uses of features that another variation of the
>     target may not have; use conditional compilation or runtime detection, as
>     appropriate, to let each target run code supported by that target.

I don't think this PR breaks anything.

r? compiler-team
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bors committed Jul 24, 2023
2 parents f475098 + ab4d65e commit 48c0c25
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Showing 9 changed files with 122 additions and 29 deletions.
14 changes: 7 additions & 7 deletions compiler/rustc_target/src/spec/aarch64_unknown_hermit.rs
Original file line number Diff line number Diff line change
@@ -1,15 +1,15 @@
use crate::spec::Target;
use crate::spec::{Target, TargetOptions};

pub fn target() -> Target {
let mut base = super::hermit_base::opts();
base.max_atomic_width = Some(128);
base.features = "+v8a,+strict-align,+neon,+fp-armv8".into();

Target {
llvm_target: "aarch64-unknown-hermit".into(),
pointer_width: 64,
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".into(),
arch: "aarch64".into(),
options: base,
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".into(),
options: TargetOptions {
features: "+v8a,+strict-align,+neon,+fp-armv8".into(),
max_atomic_width: Some(128),
..super::hermit_base::opts()
},
}
}
14 changes: 4 additions & 10 deletions compiler/rustc_target/src/spec/hermit_base.rs
Original file line number Diff line number Diff line change
@@ -1,21 +1,15 @@
use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, TargetOptions, TlsModel};

pub fn opts() -> TargetOptions {
let pre_link_args = TargetOptions::link_args(
LinkerFlavor::Gnu(Cc::No, Lld::No),
&["--build-id", "--hash-style=gnu", "--Bstatic"],
);

TargetOptions {
os: "hermit".into(),
linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
linker: Some("rust-lld".into()),
has_thread_local: true,
pre_link_args,
panic_strategy: PanicStrategy::Abort,
linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
tls_model: TlsModel::InitialExec,
position_independent_executables: true,
static_position_independent_executables: true,
tls_model: TlsModel::InitialExec,
has_thread_local: true,
panic_strategy: PanicStrategy::Abort,
..Default::default()
}
}
1 change: 1 addition & 0 deletions compiler/rustc_target/src/spec/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1418,6 +1418,7 @@ supported_targets! {
("msp430-none-elf", msp430_none_elf),

("aarch64-unknown-hermit", aarch64_unknown_hermit),
("riscv64gc-unknown-hermit", riscv64gc_unknown_hermit),
("x86_64-unknown-hermit", x86_64_unknown_hermit),

("riscv32i-unknown-none-elf", riscv32i_unknown_none_elf),
Expand Down
20 changes: 20 additions & 0 deletions compiler/rustc_target/src/spec/riscv64gc_unknown_hermit.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
use crate::spec::{CodeModel, RelocModel, Target, TargetOptions, TlsModel};

pub fn target() -> Target {
Target {
llvm_target: "riscv64-unknown-hermit".into(),
pointer_width: 64,
arch: "riscv64".into(),
data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),
options: TargetOptions {
cpu: "generic-rv64".into(),
features: "+m,+a,+f,+d,+c".into(),
relocation_model: RelocModel::Pic,
code_model: Some(CodeModel::Medium),
tls_model: TlsModel::LocalExec,
max_atomic_width: Some(64),
llvm_abiname: "lp64d".into(),
..super::hermit_base::opts()
},
}
}
20 changes: 10 additions & 10 deletions compiler/rustc_target/src/spec/x86_64_unknown_hermit.rs
Original file line number Diff line number Diff line change
@@ -1,19 +1,19 @@
use crate::spec::{StackProbeType, Target};
use crate::spec::{StackProbeType, Target, TargetOptions};

pub fn target() -> Target {
let mut base = super::hermit_base::opts();
base.cpu = "x86-64".into();
base.plt_by_default = false;
base.max_atomic_width = Some(64);
base.features = "+rdrnd,+rdseed".into();
base.stack_probes = StackProbeType::X86;

Target {
llvm_target: "x86_64-unknown-hermit".into(),
pointer_width: 64,
arch: "x86_64".into(),
data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
.into(),
arch: "x86_64".into(),
options: base,
options: TargetOptions {
cpu: "x86-64".into(),
features: "+rdrnd,+rdseed".into(),
plt_by_default: false,
max_atomic_width: Some(64),
stack_probes: StackProbeType::X86,
..super::hermit_base::opts()
},
}
}
1 change: 1 addition & 0 deletions src/doc/rustc/src/SUMMARY.md
Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@
- [sparc-unknown-none-elf](./platform-support/sparc-unknown-none-elf.md)
- [*-pc-windows-gnullvm](platform-support/pc-windows-gnullvm.md)
- [\*-nto-qnx-\*](platform-support/nto-qnx.md)
- [*-unknown-hermit](platform-support/hermit.md)
- [\*-unknown-netbsd\*](platform-support/netbsd.md)
- [*-unknown-openbsd](platform-support/openbsd.md)
- [\*-unknown-uefi](platform-support/unknown-uefi.md)
Expand Down
5 changes: 3 additions & 2 deletions src/doc/rustc/src/platform-support.md
Original file line number Diff line number Diff line change
Expand Up @@ -223,7 +223,7 @@ target | std | host | notes
[`aarch64-unknown-linux-ohos`](platform-support/openharmony.md) | ✓ | | ARM64 OpenHarmony |
[`aarch64-unknown-nto-qnx710`](platform-support/nto-qnx.md) | ✓ | | ARM64 QNX Neutrino 7.1 RTOS |
`aarch64-unknown-freebsd` | ✓ | ✓ | ARM64 FreeBSD
`aarch64-unknown-hermit` | ✓ | | ARM64 HermitCore
[`aarch64-unknown-hermit`](platform-support/hermit.md) | ✓ | | ARM64 Hermit
`aarch64-unknown-linux-gnu_ilp32` | ✓ | ✓ | ARM64 Linux (ILP32 ABI)
[`aarch64-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | ARM64 NetBSD
[`aarch64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | ARM64 OpenBSD
Expand Down Expand Up @@ -303,6 +303,7 @@ target | std | host | notes
[`riscv32imac-unknown-xous-elf`](platform-support/riscv32imac-unknown-xous-elf.md) | ? | | RISC-V Xous (RV32IMAC ISA)
[`riscv32imc-esp-espidf`](platform-support/esp-idf.md) | ✓ | | RISC-V ESP-IDF
[`riscv32imac-esp-espidf`](platform-support/esp-idf.md) | ✓ | | RISC-V ESP-IDF
[`riscv64gc-unknown-hermit`](platform-support/hermit.md) | ✓ | | RISC-V Hermit
`riscv64gc-unknown-freebsd` | | | RISC-V FreeBSD
`riscv64gc-unknown-fuchsia` | | | RISC-V Fuchsia
`riscv64gc-unknown-linux-musl` | | | RISC-V Linux (kernel 4.20, musl 1.2.0)
Expand All @@ -327,7 +328,7 @@ target | std | host | notes
`x86_64-sun-solaris` | ? | | Deprecated target for 64-bit Solaris 10/11, illumos
`x86_64-unknown-dragonfly` | ✓ | ✓ | 64-bit DragonFlyBSD
`x86_64-unknown-haiku` | ✓ | ✓ | 64-bit Haiku
`x86_64-unknown-hermit` | ✓ | | HermitCore
[`x86_64-unknown-hermit`](platform-support/hermit.md) | ✓ | | x86_64 Hermit
`x86_64-unknown-l4re-uclibc` | ? | |
[`x86_64-unknown-linux-ohos`](platform-support/openharmony.md) | ✓ | | x86_64 OpenHarmony |
[`x86_64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 64-bit OpenBSD
Expand Down
75 changes: 75 additions & 0 deletions src/doc/rustc/src/platform-support/hermit.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,75 @@
# `*-unknown-hermit`

**Tier: 3**

The [Hermit] unikernel target allows compiling your applications into self-contained, specialized unikernel images that can be run in small virtual machines.

[Hermit]: https://github.com/hermitcore

Target triplets available so far:

- `x86_64-unknown-hermit`
- `aarch64-unknown-hermit`
- `riscv64gc-unknown-hermit`

## Target maintainers

- Stefan Lankes ([@stlankes](https://github.com/stlankes))
- Martin Kröning ([@mkroening](https://github.com/mkroening))

## Requirements

These targets only support cross-compilation.
The targets do support std.

When building binaries for this target, the Hermit unikernel is built from scratch.
The application developer themselves specializes the target and sets corresponding expectations.

The Hermit targets follow Linux's `extern "C"` calling convention.

Hermit binaries have the ELF format.

## Building the target

You can build Rust with support for the targets by adding it to the `target` list in `config.toml`.
To run the Hermit build scripts, you also have to enable your host target.
The build scripts rely on `llvm-tools` and binaries are linked using `rust-lld`, so those have to be enabled as well.

```toml
[build]
build-stage = 1
target = [
"<HOST_TARGET>",
"x86_64-unknown-hermit",
"aarch64-unknown-hermit",
"riscv64gc-unknown-hermit",
]

[rust]
lld = true
llvm-tools = true
```

## Building Rust programs

Rust does not yet ship pre-compiled artifacts for these targets.
To compile for these targets, you will either need to build Rust with the targets enabled
(see “Building the targets” above), or build your own copy of `core` by using `build-std` or similar.

Building Rust programs can be done by following the tutorial in our starter application [rusty-demo].

[rusty-demo]: https://github.com/hermitcore/rusty-demo

## Testing

The targets support running binaries in the form of self-contained unikernel images.
These images can be chainloaded by Hermit's [loader] or hypervisor ([Uhyve]).
QEMU can be used to boot Hermit binaries using the loader on any architecture.
The targets do not support running the Rust test suite.

[loader]: https://github.com/hermitcore/rusty-loader
[Uhyve]: https://github.com/hermitcore/uhyve

## Cross-compilation toolchains and C code

The targets do not yet support C code and Rust code at the same time.
1 change: 1 addition & 0 deletions src/tools/build-manifest/src/main.rs
Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,7 @@ static TARGETS: &[&str] = &[
"riscv32imac-unknown-none-elf",
"riscv32gc-unknown-linux-gnu",
"riscv64imac-unknown-none-elf",
"riscv64gc-unknown-hermit",
"riscv64gc-unknown-none-elf",
"riscv64gc-unknown-linux-gnu",
"s390x-unknown-linux-gnu",
Expand Down

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