On Tue, Jul 14, 2015 at 11:40:40AM -0400, Vivek Goyal wrote: > On Tue, Jul 14, 2015 at 03:34:30PM +0000, dwalker at fifo99.com wrote: > > On Tue, Jul 14, 2015 at 11:02:08AM -0400, Vivek Goyal wrote: > > > On Tue, Jul 14, 2015 at 01:59:19PM +0000, dwalker at fifo99.com wrote: > > > > On Mon, Jul 13, 2015 at 08:19:45PM -0500, Eric W. Biederman wrote: > > > > > dwalker at fifo99.com writes: > > > > > > > > > > > On Fri, Jul 10, 2015 at 08:41:28AM -0500, Eric W. Biederman wrote: > > > > > >> Hidehiro Kawai <hidehiro.kawai.ez at hitachi.com> writes: > > > > > >> > > > > > >> > You can call panic notifiers and kmsg dumpers before kdump by > > > > > >> > specifying "crash_kexec_post_notifiers" as a boot parameter. > > > > > >> > However, it doesn't make sense if kdump is not available. In that > > > > > >> > case, disable "crash_kexec_post_notifiers" boot parameter so that > > > > > >> > you can't change the value of the parameter. > > > > > >> > > > > > >> Nacked-by: "Eric W. Biederman" <ebiederm at xmission.com> > > > > > > > > > > > > I think it would make sense if he just replaced "kdump" with "kexec". > > > > > > > > > > It would be less insane, however it still makes no sense as without > > > > > kexec on panic support crash_kexec is a noop. So the value of the > > > > > seeting makes no difference. > > > > > > > > Can you explain more, I don't really understand what you mean. Are you suggesting > > > > the whole "crash_kexec_post_notifiers" feature has no value ? > > > > > > Daniel, > > > > > > BTW, why are you using crash_kexec_post_notifiers commandline? Why not > > > without it? > > > > It was explained in the prior thread but to rehash, the notifiers are used to do a switch > > over from the crashed machine to another redundant machine. > > So why not detect failure using polling or issue notifications from second > kernel. > > IOW, expecting that a crashed machine will be able to deliver notification > reliably is falwed to begin with, IMHO. It's flawed to think you can kexec, but you still do it right ? I've not gotten into the deep details of this switching process, but that's how this interface is used. > If a machine is failing, there are high chance it can't deliver you the > notification. Detecting that failure suing some kind of polling mechanism > might be more reliable. And it will make even kdump mechanism more > reliable so that it does not have to run panic notifiers after the crash. I think what your suggesting is that my company should change how it's hardware works and that's not really an option for me. This isn't a simple thing like checking over the network if the machine is down or not, this is way more complex hardware design. Daniel
