Re: [Qemu-devel] [PATCH v2 for-3.0] tests/libqtest: Improve kill_qemu()

[Eric Blake <eblake@redhat.com>]

On 07/25/2018 11:17 AM, Markus Armbruster wrote:

>>
>> the output was produced by bash, which uses waitpid() - and therefore
>> the fact that bash reports the core dump even when no core file is
>> created is promising.
> 
> Proof beats plausibility argument:
> 
> $ cat wcordump.c

> $ gcc -Wall -g -O wcordump.c
> $ (ulimit -c unlimited; ./a.out)
> sig 6 128
> $ (ulimit -c 0; ./a.out)
> sig 6 0

Doesn't match my results:

$ (ulimit -c 0; ./a.out)
sig 6 128

So, what's different between our two environments?

kernel 4.17.7-100.fc27.x86_64

$ echo /proc/sys/kernel/core_*
/proc/sys/kernel/core_pattern /proc/sys/kernel/core_pipe_limit 
/proc/sys/kernel/core_uses_pid
$ cat /proc/sys/kernel/core_*
|/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %e
0
1

> 
> Looks like WCOREDUMP() does depend on my ulimit -c.

Or worse, that its behavior is kernel/environment-sensitive.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org