On Thu, Jan 25, 2024 at 12:20 PM WANG Rui [off-list ref] wrote:

Hello,

On Mon, Jan 22, 2024 at 5:17 PM Trevor Gross [off-list ref] wrote:

quoted

On Fri, Oct 20, 2023 at 10:59 AM Jamie Cunliffe [off-list ref] wrote:

quoted

Eventually we want all architectures to be using the target as defined
by rustc. However currently some architectures can't do that and are
using the target.json specification. This puts in place the foundation
to allow the use of the builtin target definition or a target.json
specification.

Signed-off-by: Jamie Cunliffe <redacted>
---
 Makefile          | 1 -
 arch/x86/Makefile | 1 +
 rust/Makefile     | 5 ++++-
 scripts/Makefile  | 4 +++-
 4 files changed, 8 insertions(+), 3 deletions(-)

Adding LoongArch maintainers - this patch will need a small update to
arch/loongarch/Makefile similar to the change in arch/x86/Makefile
(included below), since that support is now in-tree and uses
generate_rust_target [1]. Also a very minor conflict in docs at patch
2/2.

I believe this patchset is still waiting on an ack from the kbuild
team. Series at [2] for reference.

Thanks,
Trevor

[1]: https://lore.kernel.org/rust-for-linux/20240108032117.215171-1-wangrui@loongson.cn/ (local)
[2]: https://lore.kernel.org/rust-for-linux/20231020155056.3495121-1-Jamie.Cunliffe@arm.com/ (local)

I can confirm that the fix patch [2], based on patch [1], is suitable
for LoongArch. LoongArch encounters no issues when using the built-in
`loongarch64-unknown-none-softfloat` target. Once patch [1] is merged
into the mainline, I'll send a patch to switch to using the built-in
target.

But, [1] and [2] must be squashed together.
Otherwise, [1] is changing the behavior of loongach,
while the commit description does not mention it.

Thanks,
Rui

[1]: https://lore.kernel.org/rust-for-linux/20231020155056.3495121-1-Jamie.Cunliffe@arm.com/ (local)
[2]: https://github.com/heiher/linux/commit/c504d83a6edd963e2ba58ec538e3f06da78b187e.patch

quoted

quoted

diff --git a/Makefile b/Makefile
index 88ebf6547964..23100f193da3 100644
--- a/Makefile
+++ b/Makefile

@@ -566,7 +566,6 @@ KBUILD_CFLAGS += -fno-strict-aliasing

 KBUILD_CPPFLAGS := -D__KERNEL__
 KBUILD_RUSTFLAGS := $(rust_common_flags) \
-                   --target=$(objtree)/scripts/target.json \
                    -Cpanic=abort -Cembed-bitcode=n -Clto=n \
                    -Cforce-unwind-tables=n -Ccodegen-units=1 \
                    -Csymbol-mangling-version=v0 \

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 5bfe5caaa444..0f339d4abd40 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile

@@ -68,6 +68,7 @@ export BITS
 #    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
 #
 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
+KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json
 KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2

 ifeq ($(CONFIG_X86_KERNEL_IBT),y)

diff --git a/rust/Makefile b/rust/Makefile
index 87958e864be0..8d75a6ffe951 100644
--- a/rust/Makefile
+++ b/rust/Makefile

@@ -428,8 +428,11 @@ $(obj)/core.o: private skip_clippy = 1
 $(obj)/core.o: private skip_flags = -Dunreachable_pub
 $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
 $(obj)/core.o: private rustc_target_flags = $(core-cfgs)
-$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs scripts/target.json FORCE
+$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
        $(call if_changed_dep,rustc_library)
+ifdef CONFIG_X86_64
+$(obj)/core.o: scripts/target.json
+endif

 $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
 $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE

diff --git a/scripts/Makefile b/scripts/Makefile
index 576cf64be667..c85d130a4125 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile

@@ -11,12 +11,14 @@ hostprogs-always-$(CONFIG_MODULE_SIG_FORMAT)                += sign-file
 hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE)    += insert-sys-cert
 hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS)                += rustdoc_test_builder
 hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS)                += rustdoc_test_gen
-always-$(CONFIG_RUST)                                  += target.json

+ifdef CONFIG_X86_64
+always-$(CONFIG_RUST)                                  += target.json
 filechk_rust_target = $< < include/config/auto.conf

 $(obj)/target.json: scripts/generate_rust_target include/config/auto.conf FORCE
        $(call filechk,rust_target)
+endif

 hostprogs += generate_rust_target
 generate_rust_target-rust := y
--

2.30.2

-- 
Best Regards
Masahiro Yamada

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