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

Nicolas Schier
2025-09-17T11:55:48Z

On Tue, Sep 16, 2025 at 02:42:48PM +0200, Nicolas Schier wrote:
> On Tue, Sep 16, 2025 at 01:30:20PM +0200, Alexey Gladkov wrote:
...
> > I think in the case of .modinfo, we can change the flag in the section
> > since we are going to delete it anyway.
> >
> > diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> > index dbbe3bf0cf23..9a118b31d0dc 100644
> > --- a/scripts/Makefile.vmlinux
> > +++ b/scripts/Makefile.vmlinux
> > @@ -87,7 +87,8 @@ remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*'
> > remove-symbols := -w --strip-symbol='__mod_device_table__*'
> >
> > quiet_cmd_strip_relocs = OBJCOPY $@
> > - cmd_strip_relocs = $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) \
> > + cmd_strip_relocs = $(OBJCOPY) $(patsubst %,--set-section-flags %=noload,$(remove-section-y)) $< && \
> > + $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) \
> > $(remove-symbols) $< $@
> >
> > targets += vmlinux
>
> Ah, great! I thought we had to fiddle around with linker scripts et al.
> I needed to use an intermediate file:
>
> diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
> index e2ceeb9e168d..516d51ca634b 100644
> --- a/scripts/Makefile.vmlinux
> +++ b/scripts/Makefile.vmlinux
> @@ -90,6 +90,9 @@ remove-section-y := .modinfo
> remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*'
>
> quiet_cmd_strip_relocs = OBJCOPY $@
> - cmd_strip_relocs = $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $< $@
> + cmd_strip_relocs = set -e; \
> + trap 'rm $<.noload' EXIT HUP INT; \
> + $(OBJCOPY) $(patsubst %,--set-section-flags %=noload,$(remove-section-y)) $< $<.noload && \
> + $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $<.noload $@
>
> targets += vmlinux

I'd like to suggest another version closer to yours, as mine has several flaws:

diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index dbbe3bf0cf23..9a118b31d0dc 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -87,7 +87,8 @@ remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*'
remove-symbols := -w --strip-symbol='__mod_device_table__*'

quiet_cmd_strip_relocs = OBJCOPY $@
- cmd_strip_relocs = $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) \
+ cmd_strip_relocs = $(OBJCOPY) $(patsubst %,--set-section-flags %=noload,$(remove-section-y)) $< $@; \
+ $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) \
$(remove-symbols) $@

targets += vmlinux

Rationale (mainly for myself to not walk into that trap too often again):

* Use ';' instead of '&&' as 'cmd_' is evaluated in a 'set -e'
environment ('cmd') and thus '&&' may hide a possible error exit
code.

* Create 'vmlinux' already with the first objcopy and let the second
one modify it in order to not need a temporary file; iff one or the
other objcopy exists with an error exit code, the 'set -e + trap'
('delete-on-interrupt') shell will remove a possibly existing
vmlinux file.

Kind regards,
Nicolas