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From: Ard Biesheuvel <ardb@kernel.org>
Date: Fri, 15 Mar 2024 13:46:21 +0100
Message-ID: <CAMj1kXEgQLizmzUwvw79DQ9zkq2L5ed5576MzmYX6uHA5QUh1Q@mail.gmail.com>
Subject: Re: [PATCH-next v3] arm32: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION
To: "liuyuntao (F)" <liuyuntao12@huawei.com>
Cc: Arnd Bergmann <arnd@arndb.de>, linux-arm-kernel@lists.infradead.org, 
	linux-kernel@vger.kernel.org, Geert Uytterhoeven <geert@linux-m68k.org>, 
	Russell King <linux@armlinux.org.uk>, Andrew Davis <afd@ti.com>, 
	Andrew Morton <akpm@linux-foundation.org>, 
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, 
	Geert Uytterhoeven <geert+renesas@glider.be>, Jonathan Corbet <corbet@lwn.net>, 
	Mike Rapoport <rppt@kernel.org>, Rob Herring <robh@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, 
	Linus Walleij <linus.walleij@linaro.org>, Fangrui Song <maskray@google.com>
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On Fri, 15 Mar 2024 at 13:22, liuyuntao (F) <liuyuntao12@huawei.com> wrote:
>
>
>
> On 2024/3/15 20:13, Ard Biesheuvel wrote:
> > On Fri, 15 Mar 2024 at 13:10, liuyuntao (F) <liuyuntao12@huawei.com> wr=
ote:
> >>
> >>
> >>
> >> On 2024/3/15 19:51, Arnd Bergmann wrote:
> >>> On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
> >>>> On 2024/3/15 18:46, Ard Biesheuvel wrote:
> >>>>> @@ -28,6 +28,7 @@
> >>>>>                                       -DEFI_HAVE_MEMCHR -DEFI_HAVE_=
STRRCHR \
> >>>>>                                       -DEFI_HAVE_STRCMP -fno-builti=
n -fpic \
> >>>>>                                       $(call cc-option,-mno-single-=
pic-base)
> >>>>> +cflags-$(CONFIG_ARM)           :=3D $(filter-out -fdata-sections, =
$(CFLAGS-y))
> >>>>>     cflags-$(CONFIG_RISCV)         +=3D -fpic -DNO_ALTERNATIVE -mno=
-relax
> >>>>>     cflags-$(CONFIG_LOONGARCH)     +=3D -fpie
> >>>>
> >>>> Another error:
> >>>> cannot initialize array of =E2=80=98short unsigned int=E2=80=99 from=
 a string literal
> >>>> with type array of =E2=80=98unsigned int=E2=80=99
> >>>>     17 | static const efi_char16_t shim_MokSBState_name[] =3D L"MokS=
BStateRT";
> >>>
> >>> The line sets cflags-y to an empty string.
> >>>
> >>> It probably should have been
> >>>
> >>> cflags-$(CONFIG_ARM)           :=3D $(filter-out -fdata-sections, $(c=
flags-y))
> >>>
> >>> (small cflags instead of CFLAGS).
> >>>
> >
> > Oops indeed.
> >
> >> Oh, my mistake, after fixed this bug, still this error:
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' fr=
om `drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.d=
ata.efi_loglevel'
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid=
' from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in se=
ction `.data.screen_info_guid'
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid' =
from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in secti=
on `.data.cpu_state_guid'
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' fro=
m `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in sec=
tion `.data.efi_nokaslr'
> >>
> >> The -fdata-sections option is present in the KBUILD_CFLAGS_KERNEL
> >> variable; altering cflags-y only affect the KBUILD_CFLAGS variable.
> >> It seems that the -fdata-sections option needs to be removed from the
> >> KBUILD_CFLAGS_KERNEL variable.
> >
> > Indeed.
> >
> > So
> >
> > KBUILD_CFLAGS_KERNEL :=3D $(filter-out -fdata-sections,$(KBUILD_CFLAGS_=
KERNEL))
> >
> > (assuming I got it right this time without build testing)
>
> Um, it not worked,too, same error.

Aren't you missing a 'L' ?

> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM)          +=3D -DEFI_HAVE_STRLEN =
-DEFI_HAVE_STRNLEN \
> >                                    -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR=
 \
> >

> > ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> > KBUILD_CFLAGS_KERNEL +=3D -ffunction-sections -fdata-sections
> > KBUILD_RUSTFLAGS_KERNEL +=3D -Zfunction-sections=3Dy
> > LDFLAGS_vmlinux +=3D --gc-sections
> > endif
>
>                                   -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> >                                    $(call cc-option,-mno-single-pic-bas=
e)
> > +KBUILD_CFLAGS_KERNE            :=3D $(filter-out -fdata-sections, $(KB=
UILD_CFLAGS_KERNE))
> >  cflags-$(CONFIG_RISCV)         +=3D -fpic -DNO_ALTERNATIVE -mno-relax
> >  cflags-$(CONFIG_LOONGARCH)     +=3D -fpie
>
>