Re: dumps & shutdown order (was Re: CVS commit: src/sys/arch)

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Mon, Jun 29, 2009 at 06:00:06PM -0500, David Young wrote:
> On Sat, Jun 27, 2009 at 03:59:39PM -0500, David Young wrote:
> > On Sat, Jun 27, 2009 at 10:18:55AM +0200, vincent%labri.fr@localhost wrote:
> > > 
> > > I think this deserves a heads-up to users because I, for one, usually
> > > hardware reboot my computer while it dumps its GBs of RAM to the disk.
> > 
> > You're absolutely right.  Let me see what I can do with the order of
> > things.  I already have some ideas in mind.  I can give the problem some
> > attention on Monday.
> 
> Looks like I can move dumps back to their customary place in the
> shutdown order by opening the dump device early in cpu_reboot(9) to
> prevent its detachment, running the detachment/unmount loop, closing
> the device, dumping, and running the detachment/unmount loop again.

I don't think you should do this.  It makes it unlikely we will ever get
a useful dump of a system which paniced from a filesystem problem.

Those who don't want dumps should...disable them.  And the sparse dump
code makes dumping even many large-memory systems very fast.