Hi John, Muhammad,
On Tue, 6 Jun 2023, John Hubbard wrote:
As per a discussion with Muhammad Usama Anjum [1], the following is how one is supposed to build selftests:
make headers && make -C tools/testing/selftests/mmChange the selftest build system's lib.mk to fail out with a helpful message if that prerequisite "make headers" has not been done yet.
[1] https://lore.kernel.org/all/bf910fa5-0c96-3707-cce4-5bcc656b6274@collabora.c...
could you, please, elaborate more on that one is supposed to build selftests with 'make headers'? Yes, Documentation/dev-tools/kselftest.rst mentions that because you might need headers but...
The common way how we test the kernel is to build the kernel, install it somewhere and run selftests on top. The sequence basically being "make rpm-pkg; rpm -ivh; cd tools/testing/selftest/livepatch/ in source tree; sudo make run_tests" (or a similar variation of the procedure). The point is that we want to test the running kernel with its respective environment installed in /lib/modules/`uname -r`/ (if needed). This way we can run newer selftests from the current mainline tree on older kernels among others.
The commit breaks the use case which worked for a long long time.
It also breaks what Marcos proposed for livepatch selftests in https://lore.kernel.org/all/20231031-send-lp-kselftests-v3-0-2b1655c2605f@su...
I guess we can always work around it by letting subsystem selftests to override KHDR_DIR but I am not comfortable with the behaviour that your commit introduced in the first place to be honest.
Thank you, Miroslav