Re: debugging a program which spawns multiple children

[Christian Groessler <chris at groessler dot org>]

On 02/15/18 20:54, John Baldwin wrote:
> On Monday, February 12, 2018 08:24:32 PM Simon Marchi wrote:
> > On 2018-02-12 08:19 PM, Christian Groessler wrote:
> > > Hi,
> > >
> > > I'm trying to debug a problem in FreeBSD's "dump" command. The dump
> > > command creates 4 or 5 child processes,
> > > and in my use case one of them gets a SIGSEGV.
> > >
> > > Is it possible to monitor all spawned processes simultaneously? I'm
> > > currently using gdb version 7.12.1 from the FreeBSD ports.
> > > I would have to problem to use a newer version of gdb and compile it
> > > locally.
> > >
> > > regards,
> > > chris
> > Hi Christian,
> >
> > If GDB for FreeBSD supports it, you can keep debugging the parent process as
> > well as child processes by using "set detach-on-fork off".  John (in CC) may
> > give more info about the support for multi process debugging with FreeBSD.
> GDB 7.12.1 from ports should support fork following as Simon noted, but that
> does only work on FreeBSD versions 9.1 and later.


I have 7.12.1 already installed and am using FreeBSD 10.3. I haven't had
time to try this gdb version it out yet...


> > You might want to read more about the "all-stop" vs "non-stop" modes in the GDB
> > documentation and their related settings.
> The FreeBSD native target only supports "all-stop" mode currently.


That should be enough. In fact, I want everything to stop when the first
SIGSEGV happens...


Thanks,
chris