Re: [PATCH] kbuild: Fail the build early when no lz4 present

Masahiro Yamada
2018-10-11T04:27:18Z

Hi Borislav,

On Thu, Oct 11, 2018 at 7:23 AM Borislav Petkov <bp@alien8.de> wrote:
>
> From: Borislav Petkov <bp@suse.de>
>
> When building randconfigs, the build fails at kernel compression stage
> due to missing lz4 on the system but CONFIG_KERNEL_LZ4 has been selected
> by randconfig. The result looks somethins like this:
>
> (cat arch/x86/boot/compressed/vmlinux.bin arch/x86/boot/compressed/vmlinux.relocs | lz4c -l -c1 stdin stdout && printf \334\141\301\001) > arch/x86/boot/compressed/vmlinux.bin.lz4 || (rm -f arch/x86/boot/compressed/vmlinux.bin.lz4 ; false)
> /bin/sh: 1: lz4c: not found

So, the cause of the failure is clear enough
from the build log.

It is weird to check only lz4c.
If CONFIG_KERNEL_LZO is enabled, but lzop is not installed,
I see this log

LZO arch/x86/boot/compressed/vmlinux.bin.lzo
/bin/sh: 1: lzop: not found

It is still clear what to do, though.

> make[2]: *** [arch/x86/boot/compressed/Makefile:143: arch/x86/boot/compressed/vmlinux.bin.lz4] Error 1
> make[1]: *** [arch/x86/boot/Makefile:112: arch/x86/boot/compressed/vmlinux] Error 2
> make: *** [arch/x86/Makefile:290: bzImage] Error 2
>
> Fail the build much earlier by checking for lz4c presence before doing
> anything else.

Is it necessary to check this earlier?

If you get this error, you just need to install the tool.
Then, you can re-run the incremental build.

BTW, this patch has a drawback.

[1] Enable CONFIG_KERNEL_LZ4 on the system
without lz4c installed

[2] Run 'make' and you will get the error
"lz4 tool not found on this system but CONFIG_KERNEL_LZ4 enabled"

[3] Run 'make menuconfig' and
switch from CONFIG_KERNEL_LZ4 to CONFIG_KERNEL_GZIP

[4] Run 'make' and you will still get the same error
even after you have chosen to use GZIP instead of LZ4.

> Signed-off-by: Borislav Petkov <bp@suse.de>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Cc: Michal Marek <michal.lkml@markovi.net>
> Cc: linux-kbuild@vger.kernel.org
> ---
> Makefile | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index a0c32de80482..f91de649234b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -788,6 +788,12 @@ KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
> LDFLAGS_vmlinux += --gc-sections
> endif
>
> +ifdef CONFIG_KERNEL_LZ4
> +ifeq ($(CONFIG_SHELL which lz4c),)
> +$(error "lz4 tool not found on this system but CONFIG_KERNEL_LZ4 enabled")
> +endif
> +endif
> +
> # arch Makefile may override CC so keep this after arch Makefile is included
> NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
>
> --
> 2.19.0.271.gfe8321ec057f
>

--
Best Regards
Masahiro Yamada