On Mon, Apr 14, 2008 at 09:46:22AM -0400, Vivek Goyal wrote: > On Fri, Apr 11, 2008 at 09:07:51PM -0700, Andrew Morton wrote: > > [..] > > > Kernel panic - not syncing: Panic by panic_module. > > > __tunable_atomic_notifier_call_chain enter > > > msg_handler:panic_event was called. > > > ipmi_wdog:wdog_panic_handler was called. > > > notifier_test: notifier_test_panic() is called. > > > notifier_test: notifier_test_panic2() is called. > > > > OK. But I don't see anywhere in here the most important piece of > > information: why do we need this feature in Linux? > > > > What are the use-cases? What is the value? etc. > > > > Often I can guess (but I like the originator to remove the guesswork). In > > this case I'm stumped - I can't see any reason why anyone would want this. > > > > Hi Andrew, > > To begin with, he wants kdb, kgdb etc to co-exist with kdump. He wants > to put all the RAS tools (who are interested in panic event) on a list > and export it to user space and let user decide in what order do the tool get > executed at panic time (based on priority). > > This brings in little bit reliability concerns for kdump due to notifier > code being run after panic. > > I think people want to use this infrastrutucure beyond RAS tools. I > remember somebody wanting to send a message to remote node after a > panic (before kdump kicks in) so that remote node can initiate failover > etc. > I know it doesn't particularly relate to this patch, but FWIW, for cases like failover, I've inserted infrastrucutre in the userspace part of kdump for Fedora/RHEL to support this sort of thing. We can run arbitrary scripts righte before and after a capture so that notifications can be sent to remote nodes in a much safer fashion than using the notifier chain after a panic. Neil -- /*************************************************** *Neil Horman *Software Engineer *Red Hat, Inc. *nhorman at redhat.com *gpg keyid: 1024D / 0x92A74FA1 *http://pgp.mit.edu ***************************************************/
