The build failure reported in [1] occurred because commit 9fc96c7c19df ("selftests: error out if kernel header files are not yet built") added a new "kernel_header_files" dependency to "all", and that triggered another, pre-existing problem. Specifically, the arm64 selftests override the emit_tests target, and that override improperly declares itself to depend upon the "all" target.
This is a problem because the "emit_tests" target in lib.mk was not intended to be overridden. emit_tests is a very simple, sequential build target that was originally invoked from the "install" target, which in turn, depends upon "all".
That approach worked for years. But with 9fc96c7c19df in place, emit_tests failed, because it does not set up all of the elaborate things that "install" does. And that caused the new "kernel_header_files" target (which depends upon $(KBUILD_OUTPUT) being correct) to fail.
Some detail: The "all" target is .PHONY. Therefore, each target that depends on "all" will cause it to be invoked again, and because dependencies are managed quite loosely in the selftests Makefiles, many things will run, even "all" is invoked several times in immediate succession. So this is not a "real" failure, as far as build steps go: everything gets built, but "all" reports a problem when invoked a second time from a bad environment.
To fix this, simply remove the unnecessary "all" dependency from the overridden emit_tests target. The dependency is still effectively honored, because again, invocation is via "install", which also depends upon "all".
An alternative approach would be to harden the emit_tests target so that it can depend upon "all", but that's a lot more complicated and hard to get right, and doesn't seem worth it, especially given that emit_tests should probably not be overridden at all.
[1] https://lore.kernel.org/20230710-kselftest-fix-arm64-v1-1-48e872844f25@kerne...
Fixes: 9fc96c7c19df ("selftests: error out if kernel header files are not yet built") Reported-by: Mark Brown broonie@kernel.org Signed-off-by: John Hubbard jhubbard@nvidia.com --- tools/testing/selftests/arm64/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile index 9460cbe81bcc..ace8b67fb22d 100644 --- a/tools/testing/selftests/arm64/Makefile +++ b/tools/testing/selftests/arm64/Makefile @@ -42,7 +42,7 @@ run_tests: all done
# Avoid any output on non arm64 on emit_tests -emit_tests: all +emit_tests: @for DIR in $(ARM64_SUBTARGETS); do \ BUILD_TARGET=$(OUTPUT)/$$DIR; \ make OUTPUT=$$BUILD_TARGET -C $$DIR $@; \
base-commit: d5fe758c21f4770763ae4c05580be239be18947d
On 7/10/23 17:56, John Hubbard wrote:
The build failure reported in [1] occurred because commit 9fc96c7c19df ("selftests: error out if kernel header files are not yet built") added a new "kernel_header_files" dependency to "all", and that triggered another, pre-existing problem. Specifically, the arm64 selftests override the emit_tests target, and that override improperly declares itself to depend upon the "all" target.
I also have a corresponding fix for selftests/riscv, which has copied the arm64 selftest approach. But I'll wait to see how reviews go here, before sending that out.
thanks,
On Mon, Jul 10, 2023 at 05:56:29PM -0700, John Hubbard wrote:
The build failure reported in [1] occurred because commit 9fc96c7c19df ("selftests: error out if kernel header files are not yet built") added a new "kernel_header_files" dependency to "all", and that triggered another, pre-existing problem. Specifically, the arm64 selftests override the emit_tests target, and that override improperly declares itself to depend upon the "all" target.
Tested-by: Mark Brown broonie@kernel.org
Thanks!
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