Re: [Qemu-devel] [PATCH 3/5] linux-user: do not avoid dumping of qemu itself

[Jamie Lokier <jamie@shareable.org>]

Paul Brook wrote:
> > >> It sounds like WCOREDUMP is one of those things that just isn't going to
> > >> work. i.e. we have to just accept the limitation and xfail the test.
> > >
> > > If this how people feel, I'll be glad to drop this patch.
> >
> > well, as I said either we fix it or we accept that the emulation is not
> > perfect and judge that this feature is worth it.
> 
> It's not quite that simple.
> 
> I think this is a case of someone blindly "fixing" a testsuite without any 
> consideration of what is actually being implemented.
> 
> IMO a host core dump is for most purposes useless[1], and dumping
> guest state to a different location is a bug.  Given the choice
> between dumping guest core in the "normal" location and setting the
> WCOREDUMP flag, the former seems much more useful.

It's a really minor corner case, but I wonder if it's worth adding a
prctl() option or some bit in the info passed to sigqueue(), to the
Linux kernel to set the WCOREDUMP flag on exit.  Meaning "app has
coredumped itself".

> [1] A host core dump may be useful for debugging qemu itself, but that's a 
> fairly specialized corner case, and not necessarily something we want to be 
> exposing to users.

It would make sense to set RLIMIT_CORE to zero very early in
qemu-user, and then someone debugging qemu-user can easily change
RLIMIT_CORE from gdb while it is running.

-- Jamie