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From: Nathan Chancellor <nathan@kernel.org>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nicolas Schier <nicolas@fjasle.eu>
Subject: Re: [PATCH] kbuild: get lib-y objects back to static library
Date: Thu, 24 Aug 2023 11:59:30 -0700	[thread overview]
Message-ID: <20230824185930.GA2025001@dev-arch.thelio-3990X> (raw)
In-Reply-To: <20230823202040.GA2236267@dev-arch.thelio-3990X>

On Wed, Aug 23, 2023 at 01:20:42PM -0700, Nathan Chancellor wrote:
> Hi Masahiro,
> 
> On Wed, Aug 23, 2023 at 09:08:16PM +0900, Masahiro Yamada wrote:
> > Revert the following two commits:
> > 
> >  - 7273ad2b08f8 ("kbuild: link lib-y objects to vmlinux forcibly when CONFIG_MODULES=y")
> >  - 7f2084fa55e6 ("[kbuild] handle exports in lib-y objects reliably")
> > 
> > Now, lib-y is back to static library again, and the link order is
> > consistent w/wo CONFIG_MODULES.
> > 
> > Since commit ddb5cdbafaaa ("kbuild: generate KSYMTAB entries by
> > modpost"), .vmlinux.export.c contains references to exported symbols.
> > If a symbol in a lib-y object is exported, that object is always linked
> > even without any explicit user in vmlinux.
> > 
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > ---
> > 
> >  Makefile | 5 -----
> >  1 file changed, 5 deletions(-)
> > 
> > diff --git a/Makefile b/Makefile
> > index 87a9eef3fb4b..71e9c65d9eae 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -1113,12 +1113,7 @@ export ARCH_DRIVERS	:= $(drivers-y) $(drivers-m)
> >  # Externally visible symbols (used by link-vmlinux.sh)
> >  
> >  KBUILD_VMLINUX_OBJS := ./built-in.a
> > -ifdef CONFIG_MODULES
> > -KBUILD_VMLINUX_OBJS += $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
> > -KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
> > -else
> >  KBUILD_VMLINUX_LIBS := $(patsubst %/,%/lib.a, $(libs-y))
> > -endif
> >  
> >  export KBUILD_VMLINUX_LIBS
> >  export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
> > -- 
> > 2.39.2
> > 
> 
> The build error that prompted 7273ad2b08f8 from [1] appears to return
> with this patch, for example:
> 
> $ make -skj"$(nproc)" ARCH=arm64 LLVM=1 O=build mrproper virtconfig all
> ...
> ERROR: modpost: "__memcat_p" [drivers/hwtracing/stm/stm_core.ko] undefined!
> ...
> 
> [1]: https://github.com/ClangBuiltLinux/linux/issues/515

One thing I forgot to note with this is this occurs when targeting arm,
arm64, hexagon, i386, powerpc, s390, and x86_64 with various in-tree
configurations (I can provide a list if necessary).

Cheers,
Nathan

  reply	other threads:[~2023-08-24 19:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-23 12:08 [PATCH] kbuild: get lib-y objects back to static library Masahiro Yamada
2023-08-23 20:20 ` Nathan Chancellor
2023-08-24 18:59   ` Nathan Chancellor [this message]
2023-08-25 16:58     ` Nick Desaulniers
2023-08-26  0:06       ` Masahiro Yamada
2023-08-26  0:55         ` Nick Desaulniers
2023-08-24  1:44 ` Masahiro Yamada
2023-08-26  2:37 ` kernel test robot

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