On 1/20/25 6:42 PM, Masahiro Yamada wrote:
> On Mon, Jan 20, 2025 at 11:30 AM Jinghao Jia <jinghao7@xxxxxxxxxxxx> wrote:
>>
>> Commit 13b25489b6f8 ("kbuild: change working directory to external
>> module directory with M=") changed kbuild working directory of bpf
>> samples to $(srctree)/samples/bpf, which broke the vmlinux path for
>> VMLINUX_BTF, as the Makefile assumes the current work directory to be
>> $(srctree):
>>
>> Makefile:316: *** Cannot find a vmlinux for VMLINUX_BTF at any of " /path/to/linux/samples/bpf/vmlinux", build the kernel or set VMLINUX_BTF like "VMLINUX_BTF=/sys/kernel/btf/vmlinux" or VMLINUX_H variable. Stop.
>>
>> Correctly refer to the kernel source directory using $(srctree).
>>
>> Fixes: 13b25489b6f8 ("kbuild: change working directory to external module directory with M=")
>> Tested-by: Ruowen Qin <ruqin@xxxxxxxxxx>
>> Signed-off-by: Jinghao Jia <jinghao7@xxxxxxxxxxxx>
>> ---
>> samples/bpf/Makefile | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
>> index 96a05e70ace3..f97295724a14 100644
>> --- a/samples/bpf/Makefile
>> +++ b/samples/bpf/Makefile
>> @@ -307,7 +307,7 @@ $(obj)/$(TRACE_HELPERS): TPROGS_CFLAGS := $(TPROGS_CFLAGS) -D__must_check=
>>
>> VMLINUX_BTF_PATHS ?= $(abspath $(if $(O),$(O)/vmlinux)) \
>> $(abspath $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux)) \
>> - $(abspath ./vmlinux)
>> + $(abspath $(srctree)/vmlinux)
>
> This is wrong and will not work for O= build.
>
> The prefix should be $(objtree)/
>
>
I thought the $(srctree)/vmlinux is a fallback when $(O) is not defined, am I
understanding it wrong here?
--Jinghao
>
>
>
>> VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
>>
>> $(obj)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL)
>> --
>> 2.48.1
>>
>
>
