linux-kernel - Re: [PATCH 1/3] MIPS: boot/compressed: Disable abicalls

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Date:   Tue, 14 Dec 2021 11:38:10 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        list@...ndingux.net, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH 1/3] MIPS: boot/compressed: Disable abicalls

On Tue, Dec 14, 2021 at 11:09 AM Paul Cercueil <paul@...pouillou.net> wrote:
>
> Hi Nathan,
>
> Le mar., déc. 14 2021 at 11:06:57 -0700, Nathan Chancellor
> <nathan@...nel.org> a écrit :
> > On Mon, Dec 13, 2021 at 10:49:12PM +0000, Paul Cercueil wrote:
> >>  Avoid complaints from Clang/LLVM by building the decompress program
> >> with
> >>  -mno-abicalls.
> >
> > What is the message?
>
> ld.lld: warning: lto.tmp: linking abicalls code with non-abicalls code
> arch/mips/kernel/head.o

That might be good to put in the commit message, as well as a link to
the corresponding issue in our issue tracker.

Though, I'm unfamiliar with that flag; removing it may allow us to
link, but it may cause problems at runtime.  It sounds like clang
supports the flag, so I have a sinking feeling this is a flag that LTO
is dropping by accident, which we've seen in the past.  Please file a
bug in the issue tracker and let's follow up there?

>
> Cheers,
> -Paul
>
> >
> >>  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> >>  ---
> >>   arch/mips/boot/compressed/Makefile | 4 ++--
> >>   1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >>  diff --git a/arch/mips/boot/compressed/Makefile
> >> b/arch/mips/boot/compressed/Makefile
> >>  index f27cf31b4140..4c9ecfbb0ef4 100644
> >>  --- a/arch/mips/boot/compressed/Makefile
> >>  +++ b/arch/mips/boot/compressed/Makefile
> >>  @@ -27,10 +27,10 @@ ifdef CONFIG_CPU_LOONGSON64
> >>   KBUILD_CFLAGS := $(filter-out -march=loongson3a, $(KBUILD_CFLAGS))
> >> -march=mips64r2
> >>   endif
> >>
> >>  -KBUILD_CFLAGS := $(KBUILD_CFLAGS) -D__KERNEL__ -D__DISABLE_EXPORTS
> >> \
> >>  +KBUILD_CFLAGS := $(KBUILD_CFLAGS) -mno-abicalls -D__KERNEL__
> >> -D__DISABLE_EXPORTS \
> >>      -DBOOT_HEAP_SIZE=$(BOOT_HEAP_SIZE)
> >> -D"VMLINUX_LOAD_ADDRESS_ULL=$(VMLINUX_LOAD_ADDRESS)ull"
> >>
> >>  -KBUILD_AFLAGS := $(KBUILD_AFLAGS) -D__ASSEMBLY__ \
> >>  +KBUILD_AFLAGS := $(KBUILD_AFLAGS) -mno-abicalls -D__ASSEMBLY__ \
> >>      -DBOOT_HEAP_SIZE=$(BOOT_HEAP_SIZE) \
> >>      -DKERNEL_ENTRY=$(VMLINUX_ENTRY_ADDRESS)
> >>
> >>  --
> >>  2.33.0
> >>
> >>
>
>


-- 
Thanks,
~Nick Desaulniers