Re: bpf selftest compiling error

[Quentin Monnet <quentin@isovalent.com>]

2022-05-19 09:21 UTC+0100 ~ Jean-Philippe Brucker <jean-philippe@linaro.org>
> Hi,
> 
> On Wed, May 18, 2022 at 10:51:44PM +0800, Shung-Hsi Yu wrote:
>> On Thu, May 12, 2022 at 06:12:36PM -0700, Vincent Li wrote:
>>> On Thu, May 12, 2022 at 5:49 PM Vincent Li <vincent.mc.li@gmail.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I cloned the bpf-next and tried to compile the bpf selftest.
>>>>
>>>> first I got error
>>>>
>>>> "
>>>> CC      /usr/src/bpf
>>>> next/tools/testing/selftests/bpf/tools/build/bpftool/xlated_dumper.o
>>>>
>>>> make[1]: *** No rule to make target
>>>> '/usr/src/bpf-next/tools/include/asm-generic/bitops/find.h', needed by
>>>> '/usr/src/bpf-next/tools/testing/selftests/bpf/tools/build/bpftool/btf_dumper.o'.
>>>> Stop.
>>
>> I also ran into the same issue on bpf-next, and the error seems rather
>> absurd as
>>
>>   1. asm-generic/bitops/find.h was removed back in 47d8c15615c0a "include:
>>      move find.h from asm_generic to linux", so perhaps this error has
>>      something to do with Makefile.asm-generic
>>   2. normal way of building bpftool with `make tools/bpf/bpftool` still
>>      works fine
>>
>> Anyway removing ARCH= CROSS_COMPILE= in the bpf selftests Makefile
>> (reverting change added in ea79020a2d9e "selftests/bpf: Enable
>> cross-building with clang") can be used as a workaround to get the build
>> working again. Adding the commit author to the thread to see if there is
>> better approach available.
> 
> Could you share the commands that lead to this error?  And did you make
> sure to clean the build tree?  I often get errors when building tools
> because my toolchains changed and some dependencies in generated .*.d
> files do not exist anymore.
> 
> I can't reproduce this specific error on today's linux-next (but found
> another issue with out-of-tree build that I'll investigate). This is what
> I run, on an x86 host for an x86 target:
> 
>  $ make defconfig
>  $ cat tools/testing/selftests/bpf/config >> .config
>    # and enable CONFIG_DEBUG_INFO_BTF
>  $ make
>  $ make -C tools/testing/selftests TARGETS=bpf SKIP_TARGETS=
> 
> Thanks,
> Jean

Hi, for what it's worth I also observed the same today in samples/bpf;
but after "make clean" the issue disappeared, and I can't reproduce it
anymore.

Quentin