Re: [PATCH] util: In ASSERT(), use "fprintf(stderr, ...)" rather than err(...)

[Laurent Vivier <lvivier@redhat.com>]

On 06/08/2024 02:27, David Gibson wrote:
> On Mon, Aug 05, 2024 at 04:10:27PM +0200, Laurent Vivier wrote:
>> We use our own implementation of assert() because the glic implementation
>> uses syscalls that aren't in our seccomp filter, see 7a8ed9459dfe
>> ("Make assertions actually useful"). And we replaced it by an err(),
>> followed by an abort() (that is also catched by seccomp).
> 
> I think Stefano's said everything I would on the change itself, but..
> 
>> We don't have a coredump or a backtrace but we have at least the
>> error message... only if logging is enabled.
> 
> Whether we get a coredump shouldn't be affected by our weird ASSERT()
> here.  If coredumps are enabled (which they're not by default on
> current distros, AFAICT), we should still get a coredump with the
> SIGSYS here, just as we would for a SIGABRT.
> 

I don't know what, but there is something that prevent passts to generate a core dump
(I tried abort(), (char *)0 = 0, it works with a simple program, not with passt).

Moreover, if we use gdb it doesn't stop on the syscall but exit and we cannot locate the 
exit point. And as strace doesn't report the syscall that generates the SIGSYS, it makes 
hard to find which one it is.

Thanks,
Laurent