On Thu, Dec 3, 2020 at 2:10 PM Andrew Delgadillo <adelg@xxxxxxxxxx> wrote: > > lib.mk defaults to gcc when CC is not set. When building selftests > as part of a kernel compilation, MAKEFLAGS is cleared to allow implicit > build rules to be used. This has the side-effect of clearing the CC > variable, which will cause selftests to be built with gcc regardless of > if we are using gcc or clang. To remedy this, propagate the CC variable > when clearing makeflags to ensure the correct compiler is used. > > Signed-off-by: Andrew Delgadillo <adelg@xxxxxxxxxx> Hi Andrew, thanks for the patch. Can you walk me through how to build the selftests? Documentation/dev-tools/kselftest.rst says: $ make -C tools/testing/selftests And if I do: $ make CC=clang defconfig $ make CC=clang -C tools/testing/selftests -j I observe a spew of errors. If I apply your patch and rerun the above, I see what looks like the same spew of errors. Am I "holding it wrong" or could the docs use a refresh? > --- > tools/testing/selftests/Makefile | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile > index d9c283503159..a4dd6d7e8276 100644 > --- a/tools/testing/selftests/Makefile > +++ b/tools/testing/selftests/Makefile > @@ -90,10 +90,12 @@ FORCE_TARGETS ?= > > # Clear LDFLAGS and MAKEFLAGS when implicit rules are missing. This provides > # implicit rules to sub-test Makefiles which avoids build failures in test > -# Makefile that don't have explicit build rules. > +# Makefile that don't have explicit build rules. Since lib.mk defaults to > +# using gcc for compilation when the CC variable is not set, we propagate the > +# CC variable so if clang is being used, selftests will build with clang. > ifeq (,$(LINK.c)) > override LDFLAGS = > -override MAKEFLAGS = > +override MAKEFLAGS = CC=$(CC) > endif > > # Append kselftest to KBUILD_OUTPUT and O to avoid cluttering > -- > 2.29.2.576.ga3fc446d84-goog > -- Thanks, ~Nick Desaulniers
