kernel module code coverage

[Michael Tuexen]

> On 8. Aug 2019, at 16:16, Slava Shwartsman <slavash at FreeBSD.org> wrote:
> 
> 
> 
> On 08-Aug-19 16:52, Alan Somers wrote:
>> On Thu, Aug 8, 2019 at 7:42 AM Michael Tuexen <tuexen at freebsd.org> wrote:
>>> 
>>> 
>>> 
>>>> On 8. Aug 2019, at 14:24, Slava Shwartsman <slavash at FreeBSD.org> wrote:
>>>> 
>>>> Apparently, Bullseye are dropping support for FreeBSD.
>>>> 
>>>> We are looking for an alternative for kernel module run time analysis.
>>>> Mostly interested in code coverage (for now).
>>>> 
>>>> Any suggestions that work for you?
>>> Have you looked into /dev/kcov. This is used by SYZKALLER for getting
>>> coverage information from the kernel.
>>> 
> 
> Thanks.
> Is there a man page for /dev/kcov?
I don't think so. There was no man page in the commit which introduced the feature:
https://svnweb.freebsd.org/base?view=revision&revision=342962

You might want to look at:
https://github.com/google/syzkaller/blob/master/tools/kcovtrace/kcovtrace.c
how to use it.

Best regards
Michael
> 
>>> Best regards
>>> Michael
>>>> 
>>>> 
>>>> Slava
>> That's part of Matt Macy's gcov project, right?.  However, while it
>> works for the kernel itself, it doesn't work for modules.
> 
> In worst case, I can build my module into the kernel, right?
> 
>> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=239194
>> -Alan
> 
> 
> Slava