On Mon, Jun 10, 2024 at 06:14:51PM GMT, Masahiro Yamada wrote:

On Mon, Jun 10, 2024 at 5:39 PM Naveen N Rao [off-list ref] wrote:

quoted

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 link-vmlinux.sh that architectures can use for this purpose.
Architectures need to select CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX and must
provide arch/<arch>/tools/vmlinux_o.sh, which will be invoked prior to
the final vmlinux link step.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
---
 arch/Kconfig            |  3 +++
 scripts/link-vmlinux.sh | 18 +++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 975dd22a2dbd..649f0903e7ef 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig

@@ -1643,4 +1643,7 @@ config CC_HAS_SANE_FUNCTION_ALIGNMENT
 config ARCH_NEED_CMPXCHG_1_EMU
        bool

+config ARCH_WANTS_PRE_LINK_VMLINUX
+       def_bool n
+
 endmenu

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 46ce5d04dbeb..07f70e105d82 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh

...

quoted

+arch_vmlinux_o=""
+if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then
+       arch_vmlinux_o=.arch.vmlinux.o
+       info "ARCH" ${arch_vmlinux_o}
+       if ! ${srctree}/arch/${SRCARCH}/tools/vmlinux_o.sh ${arch_vmlinux_o} ; then
+               echo >&2 "Failed to generate ${arch_vmlinux_o}"
+               echo >&2 "Try to disable CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX"
+               exit 1
+       fi
+fi

This is wrong because scripts/link-vmlinux.sh is not triggered
even when source files under arch/powerpc/tools/ are changed.

Presumably, scripts/Makefile.vmlinux will be the right place.

Ah, yes. Something like this?

diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index 49946cb96844..77d90b6ac53e 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux

@@ -22,6 +22,10 @@ targets += .vmlinux.export.o
 vmlinux: .vmlinux.export.o
 endif

+ifdef CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX
+vmlinux: $(srctree)/arch/$(SRCARCH)/tools/vmlinux_o.sh
+endif
+
 ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)

 # Final link of vmlinux with optional arch pass after final link

Thanks,
Naveen