Add mips-zkm-zkvm-elf triple

compiler/rustc_target/src/spec/mod.rs

@@ -1679,6 +1679,7 @@ supported_targets! {
 
     ("mips-unknown-linux-uclibc", mips_unknown_linux_uclibc),
     ("mipsel-unknown-linux-uclibc", mipsel_unknown_linux_uclibc),
+    ("mips-zkm-zkvm-elf", mips_zkm_zkvm_elf),
 
     ("i686-linux-android", i686_linux_android),
     ("x86_64-linux-android", x86_64_linux_android),

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

@@ -0,0 +1,43 @@
+use crate::abi::Endian;
+use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, TargetOptions};
+
+pub(crate) fn target() -> Target {
+    Target {
+        data_layout: "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".into(),
+        llvm_target: "mips".into(),
+        metadata: crate::spec::TargetMetadata {
+            description: Some("ZKM's zero-knowledge Virtual Machine (MIPS32r2 ISA)".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: None, // ?
+        },
+        pointer_width: 32,
+        arch: "mips".into(),
+
+        options: TargetOptions {
+            os: "zkvm".into(),
+            vendor: "zkm".into(),
+            linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
+            linker: Some("rust-lld".into()),
+            endian: Endian::Big,
+            cpu: "mips32r2".into(),
+
+            // Some crates (*cough* crossbeam) assume you have 64 bit
+            // atomics if the target name is not in a hardcoded list.
+            // Since zkvm is singlethreaded and all operations are
+            // atomic, I guess we can just say we support 64-bit
+            // atomics.
+            max_atomic_width: Some(64),
+            atomic_cas: true,
+
+            features: "+mips32r2,+soft-float,+noabicalls".into(),
+            executables: true,
+            panic_strategy: PanicStrategy::Abort,
+            relocation_model: RelocModel::Static,
+            emit_debug_gdb_scripts: false,
+            eh_frame_header: false,
+            singlethread: true,
+            ..Default::default()
+        },
+    }
+}

src/tools/build-manifest/src/main.rs

@@ -128,6 +128,7 @@ static TARGETS: &[&str] = &[
     "mipsisa64r6el-unknown-linux-gnuabi64",
     "mipsel-unknown-linux-gnu",
     "mipsel-unknown-linux-musl",
+    "mips-zkm-zkvm-elf",
     "nvptx64-nvidia-cuda",
     "powerpc-unknown-linux-gnu",
     "powerpc64-unknown-linux-gnu",