[PATCH v4 1/2] rust: Refactor the build target to allow the use of builtin targets

[Masahiro Yamada]

On Thu, Jan 25, 2024 at 12:20 PM WANG Rui <wangrui at loongson.cn> wrote:
>
> Hello,
>
> On Mon, Jan 22, 2024 at 5:17 PM Trevor Gross <tmgross at umich.edu> wrote:
> >
> > On Fri, Oct 20, 2023 at 10:59 AM Jamie Cunliffe <Jamie.Cunliffe at arm.com> wrote:
> > >
> > > 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 <Jamie.Cunliffe at arm.com>
> > > ---
> > >  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/
> > [2]: https://lore.kernel.org/rust-for-linux/20231020155056.3495121-1-Jamie.Cunliffe@arm.com/
>
> 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/
> [2]: https://github.com/heiher/linux/commit/c504d83a6edd963e2ba58ec538e3f06da78b187e.patch
>
> >
> > > 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