Add target support for RTEMS Arm

compiler/rustc_target/src/spec/mod.rs

@@ -1695,6 +1695,8 @@ supported_targets! {
     ("armv7r-none-eabihf", armv7r_none_eabihf),
     ("armv8r-none-eabihf", armv8r_none_eabihf),
 
+    ("armv7-rtems-eabihf", armv7_rtems_eabihf),
+
     ("x86_64-pc-solaris", x86_64_pc_solaris),
     ("sparcv9-sun-solaris", sparcv9_sun_solaris),
 

compiler/rustc_target/src/spec/targets/armv7_rtems_eabihf.rs

@@ -0,0 +1,35 @@
+use crate::spec::{cvs, Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, TargetOptions};
+
+pub(crate) fn target() -> Target {
+    Target {
+        llvm_target: "armv7-unknown-none-eabihf".into(),
+        metadata: crate::spec::TargetMetadata {
+            description: Some("Armv7 RTEMS (Requires RTEMS toolchain and kernel".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
+        pointer_width: 32,
+        data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),
+        arch: "arm".into(),
+
+        options: TargetOptions {
+            os: "rtems".into(),
+            families: cvs!["unix"],
+            abi: "eabihf".into(),
+            linker_flavor: LinkerFlavor::Gnu(Cc::Yes, Lld::No),
+            linker: None,
+            relocation_model: RelocModel::Static,
+            panic_strategy: PanicStrategy::Abort,
+            features: "+thumb2,+neon,+vfp3".into(),
+            max_atomic_width: Some(64),
+            emit_debug_gdb_scripts: false,
+            // GCC defaults to 8 for arm-none here.
+            c_enum_min_bits: Some(8),
+            eh_frame_header: false,
+            no_default_libraries: false,
+            env: "newlib".into(),
+            ..Default::default()
+        },
+    }
+}

library/core/Cargo.toml

@@ -43,6 +43,8 @@ check-cfg = [
     'cfg(bootstrap)',
     'cfg(no_fp_fmt_parse)',
     'cfg(stdarch_intel_sde)',
+    # #[cfg(bootstrap)] rtems
+    'cfg(target_os, values("rtems"))',
     # core use #[path] imports to portable-simd `core_simd` crate
     # and to stdarch `core_arch` crate which messes-up with Cargo list
     # of declared features, we therefor expect any feature cfg

library/core/src/ffi/mod.rs

@@ -110,7 +110,7 @@ mod c_char_definition {
             all(target_os = "android", any(target_arch = "aarch64", target_arch = "arm")),
             all(target_os = "l4re", target_arch = "x86_64"),
             all(
-                any(target_os = "freebsd", target_os = "openbsd"),
+                any(target_os = "freebsd", target_os = "openbsd", target_os = "rtems"),
                 any(
                     target_arch = "aarch64",
                     target_arch = "arm",

library/panic_unwind/Cargo.toml

@@ -20,3 +20,10 @@ cfg-if = { version = "1.0", features = ['rustc-dep-of-std'] }
 
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
 libc = { version = "0.2", default-features = false }
+
+[lints.rust.unexpected_cfgs]
+level = "warn"
+check-cfg = [
+    # #[cfg(bootstrap)] rtems
+    'cfg(target_os, values("rtems"))',
+]

library/panic_unwind/src/lib.rs

@@ -48,7 +48,7 @@ cfg_if::cfg_if! {
         target_os = "psp",
         target_os = "xous",
         target_os = "solid_asp3",
-        all(target_family = "unix", not(target_os = "espidf")),
+        all(target_family = "unix", not(any(target_os = "espidf", target_os = "rtems"))),
         all(target_vendor = "fortanix", target_env = "sgx"),
         target_family = "wasm",
     ))] {

library/std/Cargo.toml

@@ -146,4 +146,6 @@ check-cfg = [
     # and to the `backtrace` crate which messes-up with Cargo list
     # of declared features, we therefor expect any feature cfg
     'cfg(feature, values(any()))',
+    # #[cfg(bootstrap)] rtems
+    'cfg(target_os, values("rtems"))',
 ]

library/std/build.rs

@@ -53,6 +53,7 @@ fn main() {
         || target_os == "uefi"
         || target_os == "teeos"
         || target_os == "zkvm"
+        || target_os == "rtems"
 
         // See src/bootstrap/src/core/build_steps/synthetic_targets.rs
         || env::var("RUSTC_BOOTSTRAP_SYNTHETIC_TARGET").is_ok()

library/std/src/os/mod.rs

@@ -143,6 +143,8 @@ pub mod nto;
 pub mod openbsd;
 #[cfg(target_os = "redox")]
 pub mod redox;
+#[cfg(target_os = "rtems")]
+pub mod rtems;
 #[cfg(target_os = "solaris")]
 pub mod solaris;
 #[cfg(target_os = "solid_asp3")]