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

[Randy Dunlap]

On 10/10/18 3:23 PM, Borislav Petkov wrote:
> From: Borislav Petkov <bp@xxxxxxx>
> 
> 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
>   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.
> 
> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
> Cc: linux-kbuild@xxxxxxxxxxxxxxx
> ---
>  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),)

Hi,
I have been informed in the past the POSIX spells "which" as "command -v" and
hence requested to do s/which/command -v/

> +$(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)
>  
> 

cheers,
-- 
~Randy