On Thu, Oct 10, 2024 at 6:57 PM Hari Bathini [off-list ref] wrote:

On 09/10/24 8:53 pm, Masahiro Yamada wrote:

quoted

On Mon, Sep 16, 2024 at 5:58 AM Hari Bathini [off-list ref] wrote:

quoted

From: Naveen N Rao <naveen@kernel.org>

On powerpc, we would like to be able to make a pass on vmlinux.o and
generate a new object file to be linked into vmlinux. Add a generic pass
in Makefile.vmlinux that architectures can use for this purpose.

Architectures need to select CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX and must
provide arch/<arch>/tools/Makefile with .arch.vmlinux.o target, which
will be invoked prior to the final vmlinux link step.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---

Changes in v5:
* Intermediate files named .vmlinux.arch.* instead of .arch.vmlinux.*


  arch/Kconfig             | 6 ++++++
  scripts/Makefile.vmlinux | 7 +++++++
  scripts/link-vmlinux.sh  | 7 ++++++-
  3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 975dd22a2dbd..ef868ff8156a 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig

@@ -1643,4 +1643,10 @@ config CC_HAS_SANE_FUNCTION_ALIGNMENT
  config ARCH_NEED_CMPXCHG_1_EMU
         bool

+config ARCH_WANTS_PRE_LINK_VMLINUX
+       def_bool n

Redundant default. This line should be "bool".

quoted

+       help
+         An architecture can select this if it provides arch/<arch>/tools/Makefile
+         with .arch.vmlinux.o target to be linked into vmlinux.
+
  endmenu

diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index 49946cb96844..edf6fae8d960 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux

@@ -22,6 +22,13 @@ targets += .vmlinux.export.o
  vmlinux: .vmlinux.export.o
  endif

+ifdef CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX
+vmlinux: arch/$(SRCARCH)/tools/.vmlinux.arch.o

If you move this to arch/*/tools/, there is no reason
to make it a hidden file.

Thanks for reviewing and the detailed comments, Masahiro.

quoted

vmlinux: arch/$(SRCARCH)/tools/vmlinux.arch.o

quoted

+arch/$(SRCARCH)/tools/.vmlinux.arch.o: vmlinux.o

FORCE is missing.

I dropped FORCE as it was rebuilding vmlinux on every invocation
of `make` irrespective of whether vmlinux.o changed or not..

It is because you did not add vmlinux.arch.S to 'targets'

See my comment in 12/17.

  targets += vmlinux.arch.S

Just curious if the changes you suggested makes FORCE necessary
or FORCE was expected even without the other changes you suggested?

FORCE is necessary.

arch/powerpc/tools/Makefile must be checked every time.


When arch/powerpc/tools/ftrace-gen-ool-stubs.sh is changed,
vmlinux must be relinked.

Thanks
Hari

--
Best Regards
Masahiro Yamada