On Thu, 23 Mar 2023 at 09:08, Mark Brown broonie@kernel.org wrote:

I've been trying to do some stuff with KUnit but I can't seem to find a current tree where KUnit builds. Running on Debian stable starting from a clean -next tree and running:

./tools/testing/kunit/kunit.py config ./tools/testing/kunit/kunit.py build

based on Documentation/dev-tools/kunit/start.rst. However I get:

[00:42:59] Configuring KUnit Kernel ... [00:42:59] Building KUnit Kernel ... Populating config with: $ make ARCH=um O=.kunit olddefconfig Building with: $ make ARCH=um O=.kunit --jobs=8 ERROR:root:In file included from /usr/include/stdlib.h:1013, from ../arch/x86/um/os-Linux/registers.c:8: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h: In function ‘atof’: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h:26:1: error: SSE register return with SSE disabled 26 | { | ^ make[4]: *** [../scripts/Makefile.build:252: arch/x86/um/os-Linux/registers.o] Error 1 make[3]: *** [../scripts/Makefile.build:494: arch/x86/um/os-Linux] Error 2 make[3]: *** Waiting for unfinished jobs.... In file included from /usr/include/stdlib.h:1013, from ../arch/um/drivers/fd.c:7: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h: In function ‘atof’: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h:26:1: error: SSE register return with SSE disabled 26 | { | ^ make[3]: *** [../scripts/Makefile.build:252: arch/um/drivers/fd.o] Error 1 make[3]: *** Waiting for unfinished jobs.... In file included from /usr/include/stdlib.h:1013, from ../arch/um/os-Linux/skas/process.c:7: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h: In function ‘atof’: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h:26:1: error: SSE register return with SSE disabled 26 | { | ^ make[4]: *** [../scripts/Makefile.build:252: arch/um/os-Linux/skas/process.o] Error 1 make[3]: *** [../scripts/Makefile.build:494: arch/um/os-Linux/skas] Error 2 make[2]: *** [../scripts/Makefile.build:494: arch/um/os-Linux] Error 2 make[2]: *** Waiting for unfinished jobs.... make[2]: *** [../scripts/Makefile.build:494: arch/x86/um] Error 2 make[2]: *** [../scripts/Makefile.build:494: arch/um/drivers] Error 2 In file included from /usr/include/stdlib.h:1013, from arch/um/kernel/config.c:7: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h: In function ‘atof’: /usr/include/x86_64-linux-gnu/bits/stdlib-float.h:26:1: error: SSE register return with SSE disabled 26 | { | ^ make[3]: *** [../scripts/Makefile.build:252: arch/um/kernel/config.o] Error 1 make[3]: *** Waiting for unfinished jobs.... make[2]: *** [../scripts/Makefile.build:494: arch/um/kernel] Error 2 make[1]: *** [/home/broonie/git/bisect/Makefile:2028: .] Error 2 make: *** [Makefile:226: __sub-make] Error 2

[00:43:20] Elapsed time: 20.233s

Hi Mark,

This one is my fault, I'm afraid. We're triggering a bug in older gcc versions (<11) at the moment.

Patch to work around it is here, or it should be fine with gcc >= 11 or clang: https://lore.kernel.org/linux-um/20230318041555.4192172-1-davidgow@google.co...

(The gcc bug is described here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99652 )

which isn't ideal. v6.2 is also broken, albeit differently:

ERROR:root:`.exit.text' referenced in section `.uml.exitcall.exit' of arch/um/drivers/virtio_uml.o: defined in discarded section `.exit.text' of arch/um/drivers/virtio_uml.o collect2: error: ld returned 1 exit status make[2]: *** [../scripts/Makefile.vmlinux:35: vmlinux] Error 1 make[1]: *** [/home/broonie/git/linux/Makefile:1264: vmlinux] Error 2 make: *** [Makefile:242: __sub-make] Error 2

Hmm... I haven't seen this one here: v6.2 builds and runs fine with gcc 10, 11, and clang 14.

Looks like maybe it's an issue with older binutils. Maybe this patch will fix it: https://lore.kernel.org/all/20230207164156.537378-1-masahiroy@kernel.org/

which makes bisecting a bit of an issue. The kunit-fixes, kunit and kunit-next trees in -next have the former error. Can anyone point me at a tree/config/commands that's suitable for working on KUnit at the minute?

The most convenient workarounds (other than having newer gcc / binutils) are probably to either run against a different architecture (e.g. --arch x86_64) or to build with clang (--make_options LLVM=1). Those should be a bit more stable for bisections than UML on the older gcc versions.

Sorry for the mess! -- David