Hi, On 2019-02-14 2:37 p.m., Brendan Higgins wrote: > This patch set proposes KUnit, a lightweight unit testing and mocking > framework for the Linux kernel. I haven't followed the entire conversation but I saw the KUnit write-up on LWN and ended up, as an exercise, giving it a try. I really like the idea of having a fast unit testing infrastructure in the kernel. Occasionally, I write userspace tests for tricky functions that I essentially write by copying the code over to a throw away C file and exercise them as I need. I think it would be great to be able to keep these tests around in a way that they can be run by anyone who wants to touch the code. I was just dealing with some functions that required some mocked up tests so I thought I'd give KUnit a try. I found writing the code very easy and the infrastructure I was testing was quite simple to mock out the hardware. However, I got a bit hung up by one issue: I was writing unit tests for code in the NTB tree which itself depends on CONFIG_PCI which cannot be enabled in UML (for what should be obvious reasons). I managed to work around this because, as luck would have it, all the functions I cared about testing were actually static inline functions in headers. So I placed my test code in the kunit folder (so it would compile) and hacked around a couple a of functions I didn't care about that would not be compiled. In the end I got it to work acceptably, but I get the impression that KUnit will not be usable for wide swaths of kernel code that can't be compiled in UML. Has there been any discussion or ideas on how to work around this so it can be more generally useful? Or will this feature be restricted roughly to non-drivers and functions in headers that don't have #ifdefs around them? If you're interested in seeing the unit tests I ended up writing you can find the commits here[1]. Thanks, Logan [1] https://github.com/sbates130272/linux-p2pmem/ ntb_kunit
