Here I found my error rootcause:

My Makefile add a Werror flag, So it wil build waring as error as the follow code

../arch/um/os-Linux/signal.c: In function \xe2\x80\x98sig_handler_common\xe2\x80\x99: ../arch/um/os-Linux/signal.c:51:1: error: the frame size of 2960 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] } ^ ../arch/um/os-Linux/signal.c: In function \xe2\x80\x98timer_real_alarm_handler\xe2\x80\x99: ../arch/um/os-Linux/signal.c:95:1: error: the frame size of 2960 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] }

and I add the CONFIG_FRAME_WARN=4096 in arch/um/x86_64_defconfig so there was no error when I use make ARCH=um defconfig && make ARCH=um BUT I found the commit ff7b437f36b026dcd7351f86a90a0424c891dc06 has changed use make ARCH=um kunit_defconfig in kunit.py. So the error happened.

Further More, I compare the different between use x86_64_defconfig and kunit_defconfig, there is a big difference. Can We use kunit_defconfig on the basis of the x86_64_defconfig ? If the answer is ok， I would like to help add this functions

Brendan Higgins brendanhiggins@google.com 于2020年7月28日周二 上午5:29写道：

On Mon, Jul 27, 2020 at 3:01 AM Cixi Geng gengcixi@gmail.com wrote:

...

Hi Brendan: When I run kunit test in um , it failed on kernel 5.8-rc* while succeeded in v5.7 with same configuration. is this a bug?

Here is my operation: gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)

the kunitconfig: Cixi.Geng:~/git-projects/torvals-linux$ cat .kunitconfig CONFIG_KUNIT=y CONFIG_KUNIT_TEST=y CONFIG_KUNIT_EXAMPLE_TEST=y

command: Cixi.Geng:~/git-projects/torvals-linux$ ./tools/testing/kunit/kunit.py run

the Error log: [17:51:14] Configuring KUnit Kernel ... [17:51:14] Building KUnit Kernel ... ERROR:root:b"make[1]: \xe8\xbf\x9b\xe5\x85\xa5\xe7\x9b\xae\xe5\xbd\x95\xe2\x80\x9c/home/cixi.geng1/git-projects/torvals-linux/.kunit\xe2\x80\x9d\n/home/cixi.geng1/git-projects/torvals-linux/Makefile:551: recipe for target 'outputmakefile' failed\nmake[1]: \xe7\xa6\xbb\xe5\xbc\x80\xe7\x9b\xae\xe5\xbd\x95\xe2\x80\x9c/home/cixi.geng1/git-projects/torvals-linux/.kunit\xe2\x80\x9d\nMakefile:185: recipe for target '__sub-make' failed\n"

So we have a fix out for the cryptic error messages:

https://patchwork.kernel.org/patch/11652711/

But I believe it has not been picked up yet.

In the meantime, you should get more information by running

ls .kunit make ARCH=um O=.kunit

Let us know if you have any additional questions.