linux-kernel - Re: [RFC PATCH v3 6/6] powerpc: Enable build-time feature fixup processing by default

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Message-ID: <20260210212007.GA1148627@ax162>
Date: Tue, 10 Feb 2026 14:20:07 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Sathvika Vasireddy <sv@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, masahiroy@...nel.org,
	kees@...nel.org, naveen@...nel.org, jpoimboe@...nel.org,
	peterz@...radead.org, npiggin@...il.com, maddy@...ux.ibm.com,
	segher@...nel.crashing.org, christophe.leroy@...roup.eu,
	mingo@...nel.org, mpe@...erman.id.au, nsc@...nel.org
Subject: Re: [RFC PATCH v3 6/6] powerpc: Enable build-time feature fixup
 processing by default

On Mon, Feb 09, 2026 at 02:18:20PM +0530, Sathvika Vasireddy wrote:
> diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> index e3dd7fc62f20..3d2a203b8908 100644
> --- a/scripts/Makefile.vmlinux
> +++ b/scripts/Makefile.vmlinux
> @@ -88,6 +88,11 @@ remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn'
>  # https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7
>  remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel.*'
>  
> +# --emit-relocs produces .rela.* sections needed by objtool --ftr-fixup;
> +# strip them from vmlinux after fixup processing is complete.
> +remove-section-$(CONFIG_HAVE_OBJTOOL_FTR_FIXUP)    += '.rel*' '!.rel*.dyn'
> +remove-section-$(CONFIG_HAVE_OBJTOOL_FTR_FIXUP)    += '.rel.*'

Rather than duplicating the remove-section values from
CONFIG_ARCH_VMLINUX_NEEDS_RELOCS, I would like to see them combined with
something like:

diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index fcae1e432d9a..f70c3a36aee2 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -81,11 +81,15 @@ endif
 # vmlinux
 # ---------------------------------------------------------------------------
 
+# These configurations require vmlinux.unstripped to be linked with
+# '--emit-relocs', which need to be stripped from the final vmlinux.
+uses-emit-relocs := $(or $(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS),$(CONFIG_HAVE_OBJTOOL_FTR_FIXUP))
+
 remove-section-y                                   := .modinfo
-remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn'
+remove-section-$(uses-emit-relocs)                 += '.rel*' '!.rel*.dyn'
 # for compatibility with binutils < 2.32
 # https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7
-remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel.*'
+remove-section-$(uses-emit-relocs)                 += '.rel.*'
 
 remove-symbols := -w --strip-unneeded-symbol='__mod_device_table__*'