On Tue, May 18, 2021 at 7:23 AM Javier Martinez Canillas
<javierm@xxxxxxxxxx> wrote:
>
> The ccache tool can be used to speed up cross-compilation, by calling the
> compiler and binutils through ccache. For example, following should work:
>
> $ export ARCH=arm64 CROSS_COMPILE="ccache aarch64-linux-gnu-"
>
> $ make M=drivers/gpu/drm/rockchip/
>
> but pahole fails to extract the BTF info from DWARF, breaking the build:
>
> CC [M] drivers/gpu/drm/rockchip//rockchipdrm.mod.o
> LD [M] drivers/gpu/drm/rockchip//rockchipdrm.ko
> BTF [M] drivers/gpu/drm/rockchip//rockchipdrm.ko
> aarch64-linux-gnu-objcopy: invalid option -- 'J'
> Usage: aarch64-linux-gnu-objcopy [option(s)] in-file [out-file]
> Copies a binary file, possibly transforming it in the process
> ...
> make[1]: *** [scripts/Makefile.modpost:156: __modpost] Error 2
> make: *** [Makefile:1866: modules] Error 2
>
> this fails because OBJCOPY is set to "ccache aarch64-linux-gnu-copy" and
> later pahole is executed with the following command line:
>
> LLVM_OBJCOPY=$(OBJCOPY) $(PAHOLE) -J --btf_base vmlinux $@
>
> which gets expanded to:
>
> LLVM_OBJCOPY=ccache aarch64-linux-gnu-objcopy pahole -J ...
>
> instead of:
>
> LLVM_OBJCOPY="ccache aarch64-linux-gnu-objcopy" pahole -J ...
>
> Fixes: 5f9ae91f7c0 ("kbuild: Build kernel module BTFs if BTF is enabled and pahole supports it")
> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> ---
>
LGTM. Masahiro, would you like us to take this through bpf tree or
you'll apply this to kbuild one?
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> scripts/Makefile.modfinal | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> index dd87cea9fba..a7883e45529 100644
> --- a/scripts/Makefile.modfinal
> +++ b/scripts/Makefile.modfinal
> @@ -59,7 +59,7 @@ quiet_cmd_ld_ko_o = LD [M] $@
> quiet_cmd_btf_ko = BTF [M] $@
> cmd_btf_ko = \
> if [ -f vmlinux ]; then \
> - LLVM_OBJCOPY=$(OBJCOPY) $(PAHOLE) -J --btf_base vmlinux $@; \
> + LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base vmlinux $@; \
> else \
> printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \
> fi;
> --
> 2.31.1
>
