rustc_target: Add OpenEmbedded/Yocto Linux base targets

Add built-in OpenEmbedded/Yocto Linux targets for x86_64, i686,
aarch64, armv7, and riscv64.

These targets inherit from the corresponding upstream Linux
GNU targets and define OpenEmbedded-specific target triples and
linker defaults. They are intended as base targets for downstream
Yocto/OpenEmbedded-generated targets, allowing vendor-specific
targets to override only metadata (e.g. TARGET_VENDOR) while
reusing a common base configuration.

This reduces duplication in Yocto-based Rust integrations and
avoids maintaining large patch sets downstream.

Signed-off-by: Deepesh Varatharajan <Deepesh.Varatharajan@windriver.com>

Author: DeepeshWR

compiler/rustc_target/src/spec/mod.rs

@@ -1824,6 +1824,12 @@ supported_targets! {
     ("x86_64-unknown-linux-gnuasan", x86_64_unknown_linux_gnuasan),
     ("x86_64-unknown-linux-gnumsan", x86_64_unknown_linux_gnumsan),
     ("x86_64-unknown-linux-gnutsan", x86_64_unknown_linux_gnutsan),
+
+    ("aarch64-oe-linux-gnu", aarch64_oe_linux_gnu),
+    ("armv7-oe-linux-gnueabihf", armv7_oe_linux_gnueabihf),
+    ("i686-oe-linux-gnu", i686_oe_linux_gnu),
+    ("riscv64-oe-linux-gnu", riscv64_oe_linux_gnu),
+    ("x86_64-oe-linux-gnu", x86_64_oe_linux_gnu),
 }
 
 /// Cow-Vec-Str: Cow<'static, [Cow<'static, str>]>

compiler/rustc_target/src/spec/targets/aarch64_oe_linux_gnu.rs

@@ -0,0 +1,19 @@
+use crate::spec::{Target, TargetMetadata};
+
+pub(crate) fn target() -> Target {
+    let mut base = super::aarch64_unknown_linux_gnu::target();
+
+    base.metadata = TargetMetadata {
+        description: Some(
+            "64-bit Linux (kernel 3.2+, glibc 2.17+) for yocto".into(),
+        ),
+        tier: Some(3),
+        host_tools: Some(false),
+        std: Some(true),
+    };
+
+    base.llvm_target = "aarch64-oe-linux-gnu".into();
+    base.options.linker = Some("aarch64-oe-linux-gcc".into());
+
+    base
+}

compiler/rustc_target/src/spec/targets/armv7_oe_linux_gnueabihf.rs

@@ -0,0 +1,19 @@
+use crate::spec::{Target, TargetMetadata};
+
+pub(crate) fn target() -> Target {
+    let mut base = super::armv7_unknown_linux_gnueabihf::target();
+
+    base.metadata = TargetMetadata {
+        description: Some(
+            "Armv7-A Linux, hardfloat (kernel 3.2, glibc 2.17) for yocto".into(),
+        ),
+        tier: Some(3),
+        host_tools: Some(false),
+        std: Some(true),
+    };
+
+    base.llvm_target = "armv7-oe-linux-gnueabihf".into();
+    base.options.linker = Some("arm-oe-linux-gnueabi-gcc".into());
+
+    base
+}

compiler/rustc_target/src/spec/targets/i686_oe_linux_gnu.rs

@@ -0,0 +1,23 @@
+use crate::spec::{Target, TargetMetadata};
+
+pub(crate) fn target() -> Target {
+    let mut base = super::i686_unknown_linux_gnu::target();
+
+    base.metadata = TargetMetadata {
+        description: Some(
+            "32-bit Linux (kernel 3.2, glibc 2.17+) for yocto".into(),
+        ),
+        tier: Some(3),
+        host_tools: Some(false),
+        std: Some(true),
+    };
+
+    base.llvm_target = "i686-oe-linux-gnu".into();
+
+    base.options.linker = Some("i686-oe-linux-gcc".into());
+
+    base.options.cpu = "core2".into();
+    base.options.features = "+sse3".into();
+
+    base
+}

compiler/rustc_target/src/spec/targets/riscv64_oe_linux_gnu.rs

@@ -0,0 +1,19 @@
+use crate::spec::{Target, TargetMetadata};
+
+pub(crate) fn target() -> Target {
+    let mut base = super::riscv64gc_unknown_linux_gnu::target();
+
+    base.metadata = TargetMetadata {
+        description: Some(
+            "RISC-V Linux (kernel 4.20, glibc 2.29) for yocto".into(),
+        ),
+        tier: Some(3),
+        host_tools: Some(false),
+        std: Some(true),
+    };
+
+    base.llvm_target = "riscv64-oe-linux-gnu".into();
+    base.options.linker = Some("riscv64-oe-linux-gcc".into());
+
+    base
+}

compiler/rustc_target/src/spec/targets/x86_64_oe_linux_gnu.rs

@@ -0,0 +1,19 @@
+use crate::spec::{Target, TargetMetadata};
+
+pub(crate) fn target() -> Target {
+    let mut base = super::x86_64_unknown_linux_gnu::target();
+
+    base.metadata = TargetMetadata {
+        description: Some(
+            "64-bit Linux (kernel 3.2+, glibc 2.17+) for yocto".into(),
+        ),
+        tier: Some(3),
+        host_tools: Some(false),
+        std: Some(true),
+    };
+
+    base.llvm_target = "x86_64-oe-linux-gnu".into();
+    base.options.linker = Some("x86_64-oe-linux-gcc".into());
+
+    base
+}

src/doc/rustc/src/SUMMARY.md

@@ -103,6 +103,7 @@
     - [mips\*-mti-none-elf](platform-support/mips-mti-none-elf.md)
     - [mipsisa\*r6\*-unknown-linux-gnu\*](platform-support/mips-release-6.md)
     - [nvptx64-nvidia-cuda](platform-support/nvptx64-nvidia-cuda.md)
+    - [\*-oe-linux-gnu](platform-support/oe-linux-gnu.md)
     - [powerpc-unknown-openbsd](platform-support/powerpc-unknown-openbsd.md)
     - [powerpc-unknown-linux-gnuspe](platform-support/powerpc-unknown-linux-gnuspe.md)
     - [powerpc-unknown-linux-muslspe](platform-support/powerpc-unknown-linux-muslspe.md)

src/doc/rustc/src/platform-support.md

@@ -267,6 +267,7 @@ target | std | host | notes
 -------|:---:|:----:|-------
 [`aarch64-kmc-solid_asp3`](platform-support/kmc-solid.md) | ✓ |  | ARM64 SOLID with TOPPERS/ASP3
 [`aarch64-nintendo-switch-freestanding`](platform-support/aarch64-nintendo-switch-freestanding.md) | * |  | ARM64 Nintendo Switch, Horizon
+[`aarch64-oe-linux-gnu`](platform-support/oe-linux-gnu.md) | ✓ |  | ARM64 OpenEmbedded/Yocto Linux (GNU)
 [`aarch64-unknown-helenos`](platform-support/helenos.md) | ✓ |  | ARM64 HelenOS
 [`aarch64-unknown-hermit`](platform-support/hermit.md) | ✓ |  | ARM64 Hermit
 [`aarch64-unknown-illumos`](platform-support/illumos.md) | ✓ | ✓ | ARM64 illumos
@@ -309,6 +310,7 @@ target | std | host | notes
 [`armv6-unknown-freebsd`](platform-support/freebsd.md) | ✓ | ✓ | Armv6 FreeBSD
 [`armv6-unknown-netbsd-eabihf`](platform-support/netbsd.md) | ✓ | ✓ | Armv6 NetBSD w/hard-float
 [`armv6k-nintendo-3ds`](platform-support/armv6k-nintendo-3ds.md) | ? |  | Armv6k Nintendo 3DS, Horizon (Requires devkitARM toolchain)
+[`armv7-oe-linux-gnueabihf`](platform-support/oe-linux-gnu.md) | ✓ |  | ARMv7 OpenEmbedded/Yocto Linux (GNU)
 [`armv7-rtems-eabihf`](platform-support/armv7-rtems-eabihf.md) | ? |  | RTEMS OS for ARM BSPs
 [`armv7-sony-vita-newlibeabihf`](platform-support/armv7-sony-vita-newlibeabihf.md) | ✓ |  | Armv7-A Cortex-A9 Sony PlayStation Vita (requires VITASDK toolchain)
 [`armv7-unknown-freebsd`](platform-support/freebsd.md) | ✓ | ✓ | Armv7-A FreeBSD
@@ -336,6 +338,7 @@ target | std | host | notes
 [`i586-unknown-netbsd`](platform-support/netbsd.md) | ✓ |  | 32-bit x86 (original Pentium) [^x86_32-floats-x87]
 [`i586-unknown-redox`](platform-support/redox.md) | ✓ |  | 32-bit x86 Redox OS (PentiumPro) [^x86_32-floats-x87]
 [`i686-apple-darwin`](platform-support/apple-darwin.md) | ✓ | ✓ | 32-bit macOS (10.12+, Sierra+, Penryn) [^x86_32-floats-return-ABI]
+[`i686-oe-linux-gnu`](platform-support/oe-linux-gnu.md) | ✓ |  | 32-bit x86 OpenEmbedded/Yocto Linux (GNU)
 [`i686-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS (Pentium 4) [^x86_32-floats-return-ABI]
 `i686-unknown-haiku` | ✓ | ✓ | 32-bit Haiku (Pentium 4) [^x86_32-floats-return-ABI]
 [`i686-unknown-helenos`](platform-support/helenos.md) | ✓ |  | HelenOS IA-32 (see docs for pending issues)
@@ -405,6 +408,7 @@ target | std | host | notes
 [`riscv32imc-esp-espidf`](platform-support/esp-idf.md) | ✓ |  | RISC-V ESP-IDF
 [`riscv32imc-unknown-nuttx-elf`](platform-support/nuttx.md) | ✓ |  | RISC-V 32bit with NuttX
 [`riscv64-linux-android`](platform-support/android.md) | ? |  | RISC-V 64-bit Android
+[`riscv64-oe-linux-gnu`](platform-support/oe-linux-gnu.md) | ✓ |  | RISC-V OpenEmbedded/Yocto Linux (GNU)
 [`riscv64-wrs-vxworks`](platform-support/vxworks.md) | ✓ |  |
 `riscv64gc-unknown-freebsd` | ? |  | RISC-V FreeBSD
 `riscv64gc-unknown-fuchsia` | ? |  | RISC-V Fuchsia
@@ -442,6 +446,7 @@ target | std | host | notes
 [`x86_64-apple-tvos`](platform-support/apple-tvos.md) | ✓ |  | x86 64-bit tvOS
 [`x86_64-apple-watchos-sim`](platform-support/apple-watchos.md) | ✓ |  | x86 64-bit Apple WatchOS simulator
 [`x86_64-lynx-lynxos178`](platform-support/lynxos178.md) |  |  | x86_64 LynxOS-178
+[`x86_64-oe-linux-gnu`](platform-support/oe-linux-gnu.md) | ✓ |  | x86 64-bit OpenEmbedded/Yocto Linux (GNU)
 [`x86_64-pc-cygwin`](platform-support/x86_64-pc-cygwin.md) | ✓ |  | 64-bit x86 Cygwin |
 [`x86_64-pc-nto-qnx710`](platform-support/nto-qnx.md) | ✓ |  | x86 64-bit QNX Neutrino 7.1 RTOS with default network stack (io-pkt) |
 [`x86_64-pc-nto-qnx710_iosock`](platform-support/nto-qnx.md) | ✓ |  | x86 64-bit QNX Neutrino 7.1 RTOS with new network stack (io-sock) |

src/doc/rustc/src/platform-support/oe-linux-gnu.md

@@ -0,0 +1,41 @@
+# `*-oe-linux-gnu`
+
+**Tier: 3**
+
+Targets for OpenEmbedded/Yocto-based Linux systems.
+
+Target triplets available:
+
+* `x86_64-oe-linux-gnu`
+* `aarch64-oe-linux-gnu`
+* `i686-oe-linux-gnu`
+* `armv7-oe-linux-gnueabihf`
+* `riscv64-oe-linux-gnu`
+
+## Target maintainers
+
+[@DeepeshWR](https://github.com/DeepeshWR)
+
+## Requirements
+
+### Operating System
+
+These targets are intended for Linux systems built using the OpenEmbedded and Yocto Project build systems.
+
+### C Toolchain
+
+The targets use the architecture-specific OpenEmbedded GCC driver as the default linker and therefore require the corresponding OpenEmbedded cross-compilation toolchain to be available in the build environment.
+
+## Building
+
+These targets are intended for use with the OpenEmbedded/Yocto build system. They serve as base targets for downstream Yocto configurations.
+
+## Building Rust programs
+
+These targets are intended to serve as base OpenEmbedded targets. Downstream Yocto-generated targets may inherit from them and customize metadata or vendor-specific configuration.
+
+Rust does not currently ship precompiled artifacts for these targets.
+
+## Cross-compilation toolchains and C code
+
+The targets support linking with C code through the corresponding OpenEmbedded cross-compilation toolchains.