Re: [PATCH v4 00/14] kbuild: yet another series of cleanups (modpost, LTO, MODULE_REL_CRCS, export.h)

Masahiro Yamada
2022-05-10T06:57:19Z

On Tue, May 10, 2022 at 7:13 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> On Mon, May 09, 2022 at 01:24:33PM +0900, Masahiro Yamada wrote:
> > On Mon, May 9, 2022 at 4:09 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > This is the third batch of cleanups in this development cycle.
> > >
> > > Major changes in v4:
> > > - Move static EXPORT_SYMBOL check to a script
> > > - Some refactoring
> > >
> > > Major changes in v3:
> > >
> > > - Generate symbol CRCs as C code, and remove CONFIG_MODULE_REL_CRCS.
> > >
> > > Major changes in v2:
> > >
> > > - V1 did not work with CONFIG_MODULE_REL_CRCS.
> > > I fixed this for v2.
> > >
> > > - Reflect some review comments in v1
> > >
> > > - Refactor the code more
> > >
> > > - Avoid too long argument error
> >
> > This series is available at
> > git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
> > lto-cleanup-v4
>
> Hi Masahiro,
>
> I checked this out and went to run it through my QEMU tests but I see
> two new errors.
>
> Failure #1:
>
> In file included from scripts/mod/section-check.c:3:
> scripts/mod/modpost.h:15:10: fatal error: 'elfconfig.h' file not found
> #include "elfconfig.h"
> ^~~~~~~~~~~~~
> 1 error generated.
>
> I was able to get past that with
>
> diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
> index ca739c6c68a1..c33b83bfbcad 100644
> --- a/scripts/mod/Makefile
> +++ b/scripts/mod/Makefile
> @@ -16,7 +16,7 @@ targets += $(devicetable-offsets-file) devicetable-offsets.s
>
> # dependencies on generated files need to be listed explicitly
>
> -$(obj)/modpost.o $(obj)/file2alias.o $(obj)/sumversion.o: $(obj)/elfconfig.h
> +$(obj)/modpost.o $(obj)/file2alias.o $(obj)/sumversion.o $(obj)/section-check.o: $(obj)/elfconfig.h
> $(obj)/file2alias.o: $(obj)/$(devicetable-offsets-file)
>

Thanks for testing.

I will slightly refactor the code as follows.

@@ -16,7 +16,7 @@ targets += $(devicetable-offsets-file) devicetable-offsets.s

# dependencies on generated files need to be listed explicitly

-$(obj)/modpost.o $(obj)/file2alias.o $(obj)/sumversion.o: $(obj)/elfconfig.h
+$(addprefix $(obj)/, $(modpost-objs)): $(obj)/elfconfig.h

$(obj)/file2alias.o: $(obj)/$(devicetable-offsets-file)

quiet_cmd_elfconfig = MKELF $@

> quiet_cmd_elfconfig = MKELF $@
>
> Failure #2:
>
> GEN .version
> CHK include/generated/compile.h
> GEN .tmp_initcalls.lds
> LTO vmlinux.o
> OBJTOOL vmlinux.o
> MODPOST vmlinux.symvers
> MODINFO modules.builtin.modinfo
> GEN modules.builtin
> LD .tmp_vmlinux.btf
> ld.lld: error: cannot open .vmlinux.export.o: No such file or directory
> BTF .btf.vmlinux.bin.o
> pahole: .tmp_vmlinux.btf: No such file or directory
> CC .vmlinux.export.c
> LD .tmp_vmlinux.kallsyms1
> ld.lld: error: .btf.vmlinux.bin.o: unknown file type
> make[1]: *** [Makefile:1159: vmlinux] Error 1
>
> I was not really able to see what is going wrong here. Attached is the
> configuration that I ran into this with. If you need any other
> information, please let me know!

Ah, OK.
This is because .vmlinux.export.o is compiled after gen_btf.

I will swap the order in v5.

> Cheers,
> Nathan

--
Best Regards
Masahiro Yamada