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

Alexey Gladkov
2025-09-16T07:12:28Z

On Mon, Sep 15, 2025 at 07:56:16AM +0200, Nicolas Schier wrote:
> 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/
>

Hm. I missed that. I need to investigate how to fix this. Nothing comes
to mind right now.

--
Rgrds, legion