Dumpdev issue in 6.4-STABLE
freebsd at jdc.parodius.com
Fri Aug 6 23:04:20 UTC 2010
On Fri, Aug 06, 2010 at 03:37:37PM -0700, Mark Saad wrote:
> > Mark Saad wrote:
> > > > wrote:
> > > > > I then set in /boot/loader.conf
> > > > >
> > > > > dumpdev="/dev/da0s1b"
> > > >
> > > > On 8-STABLE dumpdev should be defined in rc.conf(5).
> > > > Not sure about
> > > > 6-STABLE offhand.
> > >
> > > The box dies before init is started so dumpdev in
> > rc.conf is pointless.
> > I'm afraid you can't set dumpdev from the loader.
> > In ancient times it was possible to hardcode the dumpdev
> > via the kernel configuration, but that option is long
> > gone, AFAIK.
> Oliver so how do I get a core file of what the kernel is doing ? What is the "new way" of doing this ?
Use of dumpdev in /etc/rc.conf is utilised by /etc/rc.d/dumpon. This rc
script runs /sbin/dumpon, specifying the device, which tells the kernel
what device to dump stuff to using an ioctl() call for DIOCSKERNELDUMP.
There doesn't appear to be a way to make an ioctl call from within DDB.
I would say you're basically out of luck; someone on freebsd-hackers may
know of a secret way. Otherwise I would say DDB needs to be extended to
provide a "dumpdev" command or something along those lines which would
do the ioctl() equivalent.
You can drop to DDB interactively by pressing Control-Alt-Escape. You
can examine the system state from there, but even "call doadump"
probably won't work given that the kernel doesn't know what dump device
to use (re: the ioctl() call above).
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
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