On 7/27/24 12:35 AM, Shuah Khan wrote:
On 7/15/24 04:09, Muhammad Usama Anjum wrote:
Hi Kees and All,
There are several tests in kselftest subsystem which load modules to tests the internals of the kernel. Most of these test modules are just loaded by the kselftest, their status isn't read and reported to the user logs. Hence they don't provide benefit of executing those tests.
I've found patches from Kees where he has been converting such kselftests to kunit tests [1]. The probable motivation is to move tests output of kselftest subsystem which only triggers tests without correctly reporting the results. On the other hand, kunit is there to test the kernel's internal functions which can't be done by userspace.
Kselftest: Test user facing APIs from userspace Kunit: Test kernel's internal functions from kernelspace
This brings me to conclusion that kselftest which are loading modules to test kernelspace should be converted to kunit tests. I've noted several such kselftests.
This is just my understanding. Please mention if I'm correct above or more reasons to support kselftest test modules transformation into kunit test.
[1] https://lore.kernel.org/all/20221018082824.never.845-kees@kernel.org/
Please make sure you aren't taking away the ability to run these tests during boot.
The kunit tests are usually run at boot time. They can be run later as well. So I'm not trying to remove any functionality. Rather adding a way where failures would actually be detected.
It doesn't make sense to convert every single test especially when it is intended to be run during boot without dependencies - not as a kunit test but a regression test during boot.
I started investigating when these lib kselftests were just loading the test module without checking if test actually passed/failed (which proves that this type of kselftests can never detect regression as it doesn't process the results). It was strange. Hence I found out the conversion of such kselftests to kunit tests done by Kees and started this thread for discussion before doing actual work and sending patches.
bitmap is one example - pay attention to the config help test - bitmap one clearly states it runs regression testing during boot. Any test that says that isn't a candidate for conversion.
Please can you explain what do you mean by bitmap testing during boot? As far as I understand, the kselftests are usespace tests and are run after kernel has booted completely and userspace has started. It cannot be regarded as testing during boot.
I am going to nack any such conversions.
thanks, -- Shuah