linux-kernel - Re: [PATCH] powerpc: use always-y instead of extra-y in Makefiles

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Message-ID: <CAK7LNAQvRFVOeQhVos1T-R-Uq9ekY9Fo7HS+D=TCZziLo5TpHQ@mail.gmail.com>
Date: Sat, 7 Jun 2025 19:11:13 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, 
	Nicholas Piggin <npiggin@...il.com>, Naveen N Rao <naveen@...nel.org>, linuxppc-dev@...ts.ozlabs.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc: use always-y instead of extra-y in Makefiles

On Tue, Jun 3, 2025 at 3:50 PM Christophe Leroy
<christophe.leroy@...roup.eu> wrote:
>
>
>
> Le 02/06/2025 à 18:32, Masahiro Yamada a écrit :
> > The extra-y syntax is planned for deprecation because it is similar
> > to always-y.
> >
> > When building the boot wrapper, always-y and extra-y are equivalent.
> > Use always-y instead.
> >
> > In arch/powerpc/kernel/Makefile, I added ifdef KBUILD_BUILTIN to
> > keep the current behavior: prom_init_check is skipped when building
> > only modular objects.
>
> I don't understand what you mean.
>
> CONFIG_PPC_OF_BOOT_TRAMPOLINE is a bool, it cannot be a module.
>
> prom_init_check is only to check the content of prom_init.o which is
> never a module.
>
> Is always-y to run _after_ prom_init.o is built ?

The intent of "make ARCH=powerpc modules"
is to compile objects that are necessary for modules,
that is, all built-in objects are skipped.

However,
always-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += prom_init_check
would generate prom_init_check regardless,
and its prerequisite, prom_init.o as well.

With CONFIG_MODULES=y and
CONFIG_MODVERSIONS=n,
and without ifdef KBUILD_BUILTIN,

$ make ARCH=powerpc CROSS_COMPILE=powerpc64-linux-gnu-   modules

would result in this:


  CC [M]  arch/powerpc/kvm/book3s_xive_native.o
  CC [M]  arch/powerpc/kvm/book3s_64_vio.o
  LD [M]  arch/powerpc/kvm/kvm.o
  CC [M]  arch/powerpc/kvm/book3s_hv.o
  AS [M]  arch/powerpc/kvm/book3s_hv_interrupts.o
  CC [M]  arch/powerpc/kvm/book3s_64_mmu_hv.o
  CC [M]  arch/powerpc/kvm/book3s_64_mmu_radix.o
  CC [M]  arch/powerpc/kvm/book3s_hv_nested.o
  CC [M]  arch/powerpc/kvm/book3s_hv_tm.o
  LD [M]  arch/powerpc/kvm/kvm-hv.o
  CC [M]  arch/powerpc/kernel/rtas_flash.o
  CC      arch/powerpc/kernel/prom_init.o
  PROMCHK arch/powerpc/kernel/prom_init_check
  CC [M]  kernel/locking/locktorture.o
  CC [M]  kernel/time/test_udelay.o
  CC [M]  kernel/time/time_test.o
  CC [M]  kernel/backtracetest.o
  CC [M]  kernel/torture.o
  CC [M]  kernel/resource_kunit.o
  CC [M]  kernel/sysctl-test.o
  CC [M]  fs/ext4/inode-test.o
  LD [M]  fs/ext4/ext4-inode-test.o
  CC [M]  fs/fat/namei_vfat.o
  LD [M]  fs/fat/vfat.o
  CC [M]  fs/fat/fat_test.o
  CC [M]  fs/nls/nls_ucs2_utils.o
  CC [M]  fs/netfs/buffered_read.o
  CC [M]  fs/netfs/buffered_write.o
...



You can see these two lines:

  CC      arch/powerpc/kernel/prom_init.o
  PROMCHK arch/powerpc/kernel/prom_init_check

are supposed to be skipped when "make modules",
but actually compiled without ifdef.

So, I added ifdef KBUILD_BUILTIN to preserve
the current behavior.







> Christophe
>
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> > ---
> >
> >   arch/powerpc/boot/Makefile   | 6 +++---
> >   arch/powerpc/kernel/Makefile | 4 +++-
> >   2 files changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
> > index 184d0680e661..b003f7ac8755 100644
> > --- a/arch/powerpc/boot/Makefile
> > +++ b/arch/powerpc/boot/Makefile
> > @@ -242,13 +242,13 @@ $(obj)/wrapper.a: $(obj-wlib) FORCE
> >   hostprogs   := addnote hack-coff mktree
> >
> >   targets             += $(patsubst $(obj)/%,%,$(obj-boot) wrapper.a) zImage.lds
> > -extra-y              := $(obj)/wrapper.a $(obj-plat) $(obj)/empty.o \
> > +always-y     := $(obj)/wrapper.a $(obj-plat) $(obj)/empty.o \
> >                  $(obj)/zImage.lds $(obj)/zImage.coff.lds $(obj)/zImage.ps3.lds
> >
> >   dtstree             := $(src)/dts
> >
> >   wrapper             := $(src)/wrapper
> > -wrapperbits  := $(extra-y) $(addprefix $(obj)/,addnote hack-coff mktree) \
> > +wrapperbits  := $(always-y) $(addprefix $(obj)/,addnote hack-coff mktree) \
> >                       $(wrapper) FORCE
> >
> >   #############
> > @@ -455,7 +455,7 @@ WRAPPER_DTSDIR := /usr/lib/kernel-wrapper/dts
> >   WRAPPER_BINDIR := /usr/sbin
> >   INSTALL := install
> >
> > -extra-installed              := $(patsubst $(obj)/%, $(DESTDIR)$(WRAPPER_OBJDIR)/%, $(extra-y))
> > +extra-installed              := $(patsubst $(obj)/%, $(DESTDIR)$(WRAPPER_OBJDIR)/%, $(always-y))
> >   hostprogs-installed := $(patsubst %, $(DESTDIR)$(WRAPPER_BINDIR)/%, $(hostprogs))
> >   wrapper-installed   := $(DESTDIR)$(WRAPPER_BINDIR)/wrapper
> >   dts-installed               := $(patsubst $(dtstree)/%, $(DESTDIR)$(WRAPPER_DTSDIR)/%, $(wildcard $(dtstree)/*.dts))
> > diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> > index 4d2daa8e7bca..ac01cedad107 100644
> > --- a/arch/powerpc/kernel/Makefile
> > +++ b/arch/powerpc/kernel/Makefile
> > @@ -201,7 +201,9 @@ obj-$(CONFIG_ALTIVEC)             += vector.o
> >
> >   obj-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += prom_init.o
> >   obj64-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += prom_entry_64.o
> > -extra-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += prom_init_check
> > +ifdef KBUILD_BUILTIN
> > +always-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += prom_init_check
> > +endif
> >
> >   obj-$(CONFIG_PPC64)         += $(obj64-y)
> >   obj-$(CONFIG_PPC32)         += $(obj32-y)
>


-- 
Best Regards
Masahiro Yamada