From 9f6e6872c21a467af8946381e40b9021cf18066c Mon Sep 17 00:00:00 2001
From: Sean Cross <sean@xobs.io>
Date: Tue, 31 May 2022 16:15:40 +0800
Subject: [PATCH] riscv32imac-unknown-xous-elf: add target

Xous is a microkernel operating system designed to run on small systems.
The kernel contains a wide range of userspace processes that provide
common services such as console output, networking, and time access.

The kernel and its services are completely written in Rust using a
custom build of libstd. This adds support for this target to upstream
Rust so that we can drop support for our out-of-tree `target.json` file.

Add a Tier 3 target for Xous running on RISC-V.

Signed-off-by: Sean Cross <sean@xobs.io>
---
 compiler/rustc_target/src/spec/mod.rs         |  1 +
 .../src/spec/riscv32imac_unknown_xous_elf.rs  | 24 +++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 compiler/rustc_target/src/spec/riscv32imac_unknown_xous_elf.rs

diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 6dd245b047c..07d5edc0a84 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -983,6 +983,7 @@ supported_targets! {
     ("riscv32imc-unknown-none-elf", riscv32imc_unknown_none_elf),
     ("riscv32imc-esp-espidf", riscv32imc_esp_espidf),
     ("riscv32imac-unknown-none-elf", riscv32imac_unknown_none_elf),
+    ("riscv32imac-unknown-xous-elf", riscv32imac_unknown_xous_elf),
     ("riscv32gc-unknown-linux-gnu", riscv32gc_unknown_linux_gnu),
     ("riscv32gc-unknown-linux-musl", riscv32gc_unknown_linux_musl),
     ("riscv64imac-unknown-none-elf", riscv64imac_unknown_none_elf),
diff --git a/compiler/rustc_target/src/spec/riscv32imac_unknown_xous_elf.rs b/compiler/rustc_target/src/spec/riscv32imac_unknown_xous_elf.rs
new file mode 100644
index 00000000000..b46ca159370
--- /dev/null
+++ b/compiler/rustc_target/src/spec/riscv32imac_unknown_xous_elf.rs
@@ -0,0 +1,24 @@
+use crate::spec::{LinkerFlavor, LldFlavor, PanicStrategy, RelocModel};
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        data_layout: "e-m:e-p:32:32-i64:64-n32-S128".into(),
+        llvm_target: "riscv32".into(),
+        pointer_width: 32,
+        arch: "riscv32".into(),
+
+        options: TargetOptions {
+            os: "xous".into(),
+            linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
+            linker: Some("rust-lld".into()),
+            cpu: "generic-rv32".into(),
+            max_atomic_width: Some(32),
+            features: "+m,+a,+c".into(),
+            executables: true,
+            panic_strategy: PanicStrategy::Abort,
+            relocation_model: RelocModel::Static,
+            ..Default::default()
+        },
+    }
+}