svn commit: r212964 - head/sys/kern

[John Baldwin]

On Wednesday, September 22, 2010 11:23:37 am Gavin Atkinson wrote:
> On Wed, 2010-09-22 at 17:43 +0300, Andriy Gapon wrote:
> > on 22/09/2010 16:46 Gavin Atkinson said the following:
> > > Ignoring the rest of the discussion about locking, I think this is a
> > > step in the right direction.  However, what I feel we should be strongly
> > > considering is for textdumps to be enabled by default on release media.
> > > 
> > > As more groups choose to use the kernels from the release media (PC-BSD,
> > > FreeNAS, etc) and put them into places where end users are never
> > > expected to recompile kernels, having textdumps enabled by default in
> > > RELEASE kernels becomes a bigger and bigger priority.  Groups like
> > > PC-BSD don't necessarily have the time or skills to do the needed kernel
> > > debugging (and nor should they have to, it's not their purpose), so
> > > anything we can do in releases to make sure we have enough info to
> > > resolve panics seen by their users is a big bonus.
> > > 
> > > Is there any real reason why we shouldn't go down this route?
> > 
> > textdumps need DDB.
> > textdumps also need dumpdev which is not enabled by default in
> > /etc/defaults/rc.conf, but that's easier to fix for any individual user or a
> > FreeBSD "distribution".
> 
> Indeed, I was happy to see dumpdev enabled on 7.x, and disappointed to
> see it disabled on 8.x.

Agreed.  FWIW, I actually think that this is the only change needed as
crashinfo is enabled by default in 8.x and later.  We already include symbols
in kernels by default now, so just setting dumpdev will give you the same
info you generally can get from a textdump in the form of a simple
/var/crash/core.txt.N file.

The other benefit of full crashdumps + crashinfo as compared to textdumps is
that a developer can request further information in a PR followup (fire up
kgdb and enter command 'X' and reply with the output).  With a textdump any
info not collected by the textdump is lost once the machine reboots after the
crash.

-- 
John Baldwin