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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Mon, 20 Nov 2023 13:45:01 +0900
Message-ID: <CAK7LNAQi=cNK4cax76F8=f1tQC8fFRyu0SQmbiKiHTRsoat6Og@mail.gmail.com>
Subject: Re: [PATCH] loongarch: add dependency between vmlinuz.efi and vmlinux.efi
To:     Huacai Chen <chenhuacai@kernel.org>
Cc:     WANG Xuerui <kernel@xen0n.name>, loongarch@lists.linux.dev,
        linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Simon Glass <sjg@chromium.org>
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On Mon, Nov 20, 2023 at 10:33=E2=80=AFAM Huacai Chen <chenhuacai@kernel.org=
> wrote:
>
> Hi, Masahiro,
>
> On Sun, Nov 19, 2023 at 10:25=E2=80=AFPM Masahiro Yamada <masahiroy@kerne=
l.org> wrote:
> >
> > On Sun, Nov 19, 2023 at 8:59=E2=80=AFPM Huacai Chen <chenhuacai@kernel.=
org> wrote:
> > >
> > > Hi, Masahiro,
> > >
> > > On Sun, Nov 19, 2023 at 1:35=E2=80=AFPM Masahiro Yamada <masahiroy@ke=
rnel.org> wrote:
> > > >
> > > > A common issue in Makefile is a race in parallel building.
> > > >
> > > > You need to be careful to prevent multiple threads from writing to =
the
> > > > same file simultaneously.
> > > >
> > > > Commit 3939f3345050 ("ARM: 8418/1: add boot image dependencies to n=
ot
> > > > generate invalid images") addressed such a bad scenario.
> > > >
> > > > A similar symptom occurs with the following command:
> > > >
> > > >   $ make -j$(nproc) ARCH=3Dloongarch vmlinux.efi vmlinuz.efi
> > > >     [ snip ]
> > > >     SORTTAB vmlinux
> > > >     OBJCOPY arch/loongarch/boot/vmlinux.efi
> > > >     OBJCOPY arch/loongarch/boot/vmlinux.efi
> > > >     PAD     arch/loongarch/boot/vmlinux.bin
> > > >     GZIP    arch/loongarch/boot/vmlinuz
> > > >     OBJCOPY arch/loongarch/boot/vmlinuz.o
> > > >     LD      arch/loongarch/boot/vmlinuz.efi.elf
> > > >     OBJCOPY arch/loongarch/boot/vmlinuz.efi
> > > >
> > > > The log "OBJCOPY arch/loongarch/boot/vmlinux.efi" is displayed twic=
e.
> > > >
> > > > It indicates that two threads simultaneously enter arch/loongarch/b=
oot/
> > > > and write to arch/loongarch/boot/vmlinux.efi.
> > > >
> > > > It occasionally leads to a build failure:
> > > >
> > > >   $ make -j$(nproc) ARCH=3Dloongarch vmlinux.efi vmlinuz.efi
> > > >     [ snip ]
> > > >     SORTTAB vmlinux
> > > >     OBJCOPY arch/loongarch/boot/vmlinux.efi
> > > >     PAD     arch/loongarch/boot/vmlinux.bin
> > > >   truncate: Invalid number: =E2=80=98arch/loongarch/boot/vmlinux.bi=
n=E2=80=99
> > > >   make[2]: *** [drivers/firmware/efi/libstub/Makefile.zboot:13:
> > > >   arch/loongarch/boot/vmlinux.bin] Error 1
> > > >   make[2]: *** Deleting file 'arch/loongarch/boot/vmlinux.bin'
> > > >   make[1]: *** [arch/loongarch/Makefile:146: vmlinuz.efi] Error 2
> > > >   make[1]: *** Waiting for unfinished jobs....
> > > >   make: *** [Makefile:234: __sub-make] Error 2
> > > >
> > > > vmlinuz.efi depends on vmlinux.efi, but such a dependency is not
> > > > specified in arch/loongarch/Makefile.
> > > >
> > > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > > > ---
> > > >
> > > >  arch/loongarch/Makefile | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> > > > index 9eeb0c05f3f4..6022bf3d30c9 100644
> > > > --- a/arch/loongarch/Makefile
> > > > +++ b/arch/loongarch/Makefile
> > > > @@ -142,6 +142,7 @@ vdso-install-y +=3D arch/loongarch/vdso/vdso.so=
.dbg
> > > >
> > > >  all:   $(notdir $(KBUILD_IMAGE))
> > > >
> > > > +vmlinuz.efi: vmlinux.efi
> > > >  vmlinux.elf vmlinux.efi vmlinuz.efi: vmlinux
> > > >         $(Q)$(MAKE) $(build)=3D$(boot) $(bootvars-y) $(boot)/$@
> > > It is a little strange, because
> > >
> > > in drivers/firmware/efi/libstub/Makefile.zboot:
> > > vmlinuz.efi depends on vmlinuz.efi.elf, vmlinuz.efi.elf depends on
> > > vmlinuz.o, vmlinuz.o depends on vmlinuz, vmlinuz depends on
> > > vmlinux.bin, vmlinux.bin depends on $(EFI_ZBOOT_PAYLOAD).
> > >
> > > in arch/loongarch/boot/Makefile,
> > > EFI_ZBOOT_PAYLOAD :=3D vmlinux.efi
> > >
> > > So I think vmlinuz.efi has already depend on vmlinux.efi.
> >
> >
> >
> > That is a story in arch/loongarch/boot/Makefile.
> >
> >
> > I am talking about arch/loongarch/Makefile,
> > which is included from the top Makefile.
> >
> >
> > See this code.
> >
> >
> > vmlinux.elf vmlinux.efi vmlinuz.efi: vmlinux
> >         $(Q)$(MAKE) $(build)=3D$(boot) $(bootvars-y) $(boot)/$@
> >
> >
> >
> >
> > Only the required dependency is
> >
> >  - vmlinux.elf depends on vmlinux
> >  - vmlinuz.elf depends on vmlinux
> >
> >
> > vmlinux.elf and vmlinuz.elf are independent of each other.
> >
> >
> >
> > In parallel building, GNU Make considers that
> > vmlinux.elf and vmlinuz.elf can be built simultaneously.
> >
> >
> > GNU Make spawns two processes to execute these simultaneously:
> >
> >  $(MAKE) $(build)=3D$(boot) $(bootvars-y) $(boot)/vmlinux.elf
> >  $(MAKE) $(build)=3D$(boot) $(bootvars-y) $(boot)/vmlinuz.elf
> >
> >
> >
> > The former enters arch/loongarch/boot/Makefile to build
> > vmlinux.elf.  (A)
> >
> >
> > The latter also enters arch/loongarch/boot/Makefile to build
> > vmlinuz.elf, which depends on vmlinux.elf  (B)
> >
> >
> >
> > (A) and (B) are independent processes, hence none of them
> > know the other.
> >
> >
> > I hope it is clearer.
> Sorry, I'm not familiar with Makefile rules, so you are probably
> right, but should we do it like this (remove the direct dependency
> from vmlinuz.efi to vmlinux)?
>
> vmlinuz.efi: vmlinux.efi
> vmlinux.elf vmlinux.efi: vmlinux
>         $(Q)$(MAKE) $(build)=3D$(boot) $(bootvars-y) $(boot)/$@


No.

It would create only vmlinux.efi because there is
no recipe line for vmlinuz.efi


vmlinuz.efi: vmlinux.efi
        $(Q)$(MAKE) $(build)=3D$(boot) $(bootvars-y) $(boot)/$@
vmlinux.elf vmlinux.efi: vmlinux
        $(Q)$(MAKE) $(build)=3D$(boot) $(bootvars-y) $(boot)/$@


will work, but I do not want to repeat the same recipe line.


> Huacai
>
> >
> >
> >
> >
> >
> >
> > > Huacai
> > >
> > > >
> > > > --
> > > > 2.40.1
> > > >
> > > >
> > >
> >
> >
> > --
> > Best Regards
> > Masahiro Yamada


--=20
Best Regards
Masahiro Yamada