Re: [PATCH v7 3/8] kbuild: keep .modinfo section in vmlinux.unstripped

Nicolas Schier
2025-09-15T17:30:53Z

On Mon, Aug 18, 2025 at 06:54:57PM +0200, Alexey Gladkov wrote:
> From: Masahiro Yamada <masahiroy@kernel.org>
>
> Keep the .modinfo section during linking, but strip it from the final
> vmlinux.
>
> Adjust scripts/mksysmap to exclude modinfo symbols from kallsyms.
>
> This change will allow the next commit to extract the .modinfo section
> from the vmlinux.unstripped intermediate.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> include/asm-generic/vmlinux.lds.h | 2 +-
> scripts/Makefile.vmlinux | 2 +-
> scripts/mksysmap | 3 +++
> 3 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index ae2d2359b79e9..cfa63860dfd4c 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -831,6 +831,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
>
> /* Required sections not related to debugging. */
> #define ELF_DETAILS \
> + .modinfo : { *(.modinfo) } \
> .comment 0 : { *(.comment) } \
> .symtab 0 : { *(.symtab) } \
> .strtab 0 : { *(.strtab) } \
> @@ -1044,7 +1045,6 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
> *(.discard.*) \
> *(.export_symbol) \
> *(.no_trim_symbol) \
> - *(.modinfo) \
> /* ld.bfd warns about .gnu.version* even when not emitted */ \
> *(.gnu.version*) \
>
> diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> index 4f2d4c3fb7372..e2ceeb9e168d4 100644
> --- a/scripts/Makefile.vmlinux
> +++ b/scripts/Makefile.vmlinux
> @@ -86,7 +86,7 @@ endif
> # vmlinux
> # ---------------------------------------------------------------------------
>
> -remove-section-y :=
> +remove-section-y := .modinfo
> remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*'
>
> quiet_cmd_strip_relocs = OBJCOPY $@
> diff --git a/scripts/mksysmap b/scripts/mksysmap
> index 3accbdb269ac7..a607a0059d119 100755
> --- a/scripts/mksysmap
> +++ b/scripts/mksysmap
> @@ -79,6 +79,9 @@
> / _SDA_BASE_$/d
> / _SDA2_BASE_$/d
>
> +# MODULE_INFO()
> +/ __UNIQUE_ID_modinfo[0-9]*$/d
> +
> # ---------------------------------------------------------------------------
> # Ignored patterns
> # (symbols that contain the pattern are ignored)
> --
> 2.50.1
>

Hi Alexey,

with this patch applied, I still get a warning from objcpy as Masahiro
and Stephen wrote [1,2]

SORTTAB vmlinux.unstripped
+ sorttable vmlinux.unstripped
+ nm -S vmlinux.unstripped
+ ./scripts/sorttable -s .tmp_vmlinux.nm-sort vmlinux.unstripped
+ is_enabled CONFIG_KALLSYMS
+ grep -q ^CONFIG_KALLSYMS=y include/config/auto.conf
+ cmp -s System.map .tmp_vmlinux2.syms
+ echo vmlinux.unstripped: ../scripts/link-vmlinux.sh
# OBJCOPY vmlinux
objcopy --remove-section=.modinfo vmlinux.unstripped vmlinux
objcopy: vmlinux.unstripped: warning: empty loadable segment detected at vaddr=0xffff8000807a0000, is this intentional?

(arm64, allnoconfig)

Kind regards,
Nicolas

[1]: https://lore.kernel.org/linux-kbuild/CAK7LNAR-gD2H6Kk-rZjo0R3weTHCGTm0a=u2tRH1WWW6Sx6=RQ@mail.gmail.com/
[2]: https://lore.kernel.org/lkml/20250730164047.7c4a731a@canb.auug.org.au/