Initial hack at kernel build system support for Rust

Author: alex

arch/x86/x86_64-kernel-target.json

@@ -0,0 +1,33 @@
+{
+  "arch": "x86_64",
+  "cpu": "x86-64",
+  "code-model": "kernel",
+  "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+  "disable-redzone": true,
+  "eliminate-frame-pointer": false,
+  "env": "gnu",
+  "features": "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2,+soft-float",
+  "linker-flavor": "gcc",
+  "linker-is-gnu": true,
+  "llvm-target": "x86_64-elf",
+  "max-atomic-width": 64,
+  "no-compiler-rt": true,
+  "os": "none",
+  "panic-strategy": "abort",
+  "position-independent-executables": true,
+  "pre-link-args": {
+    "gcc": [
+      "-Wl,--as-needed",
+      "-Wl,-z,noexecstack",
+      "-m64"
+    ]
+  },
+  "relocation-model": "static",
+  "relro-level": "full",
+  "needs-plt": true,
+  "target-c-int-width": "32",
+  "target-endian": "little",
+  "target-family": "unix",
+  "target-pointer-width": "64",
+  "vendor": "unknown"
+}

init/Kconfig

@@ -2181,3 +2181,20 @@ config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
 # <asm/syscall_wrapper.h>.
 config ARCH_HAS_SYSCALL_WRAPPER
 	def_bool n
+
+config HAS_RUST
+        def_bool $(success,rustc --version)
+
+config HAS_CARGO
+        def_bool $(success,cargo --version)
+
+config HAS_CARGO_XBUILD
+        def_bool $(success,cargo xbuild --version)
+
+config RUST
+        bool
+        depends on HAS_RUST
+        depends on HAS_CARGO
+        depends on HAS_CARGO_XBUILD
+        help
+          Whether to support building modules written in Rust.

scripts/Makefile.build

@@ -298,6 +298,16 @@ quiet_cmd_cc_lst_c = MKLST   $@
 $(obj)/%.lst: $(src)/%.c FORCE
 	$(call if_changed_dep,cc_lst_c)
 
+# Compile Rust sources
+# --------------------
+
+ifdef CONFIG_RUST
+# TODO: release/debug
+$(obj)/%.rust.a: $(src)/Cargo.toml $(wildcard $(src)/src/*.rs) =$(srctree)/arc/$(SRCARCH)/$(ARCH)-kernel-target.json
+	cd $(src); env -u MAKE -u MAKEFLAGS cargo xbuild --target=$(srctree)/arc/$(SRCARCH)/$(ARCH)-kernel-target.json
+	cp $(src)/target/x86_64-linux-kernel-module/debug/lib%.a $(obj)/%.rust.a
+endif
+
 # header test (header-test-y, header-test-m target)
 # ---------------------------------------------------------------------------