ubuntu_bpf always fails to build with kernels >= 5.15 (ERROR: Kernel configuration is invalid.)

[Andrea Righi]

I'm getting the following error if I try to run the ubuntu_bpf kernel test with the latest linux-unstable 5.15:

  ERROR: Kernel configuration is invalid.
         include/generated/autoconf.h or include/config/auto.conf are missing.
         Run 'make oldconfig && make prepare' on kernel src to fix it.

Makefile:669: include/config/auto.conf: No such file or directory

The kernel doesn't even try to build, because we're missing a valid .config (and probably we're also missing a `make modules_prepare` in the kernel source directory).

[Po-Hsu Lin (cypressyew)]

Partial test log on jammy-oracle 5.15.0-1001.3

   TEST-OBJ [test_progs] xdp_noinline.test.o
   TEST-OBJ [test_progs] xdp_perf.test.o
   TEST-HDR [test_progs] tests.h
   EXT-OBJ [test_progs] test_progs.o
   EXT-OBJ [test_progs] cgroup_helpers.o
   EXT-OBJ [test_progs] trace_helpers.o
   EXT-OBJ [test_progs] network_helpers.o
   EXT-OBJ [test_progs] testing_helpers.o
   EXT-OBJ [test_progs] btf_helpers.o
   BINARY urandom_read
   MOD bpf_testmod.ko

   ERROR: Kernel configuration is invalid.
          include/generated/autoconf.h or include/config/auto.conf are missing.
          Run 'make oldconfig && make prepare' on kernel src to fix it.

 Makefile:669: include/config/auto.conf: No such file or directory
 make[3]: *** [Makefile:748: include/config/auto.conf] Error 1
 make[2]: *** [Makefile:16: all] Error 2
 make[1]: Leaving directory '/home/ubuntu/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf'
 make[1]: *** [Makefile:175: /home/ubuntu/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/bpf_testmod.ko] Error 2
 make: Leaving directory '/home/ubuntu/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests'
 make: *** [Makefile:162: all] Error 2

Please find attachment for the full test log.

[Po-Hsu Lin (cypressyew)]

https://git.launchpad.net/~canonical-kernel-team/+git/autotest-client-tests/commit/?id=6f3326d69074b17d296bba37da56b917af3abfe9