On Wed, Apr 17, 2013 at 02:49:59PM -0700, Eric W. Biederman wrote: > Don Zickus <dzickus at redhat.com> writes: > > > A common problem with kdump is that during the boot up of the > > second kernel, the hardware watchdog times out and reboots the > > machine before a vmcore can be captured. > > > > Instead of tellling customers to disable their hardware watchdog > > timers, I hacked up a hook to put in the kdump path that provides > > one last kick before jumping into the second kernel. > > > > The assumption is the watchdog timeout is at least 10-30 seconds > > long, enough to get the second kernel to userspace to kick the watchdog > > again, if needed. > > Why not double the watchdog timeout? and/or pet the watchdog a little > more frequently. > > This is the least icky hook I have seen proposed to be put on the kexec > on panic path, but I still suspect this may reduce the ability to take a > crash dump. What happens if it was the watchdog timer that panic'd for > example. > That should be addressed by the use of mutex_trylock(), which should fail in that case. Guenter
