On Wed, Nov 19, 2014 at 09:41:05AM -0500, Don Zickus wrote: > On Tue, Nov 18, 2014 at 05:02:54PM -0500, Dave Jones wrote: > > On Tue, Nov 18, 2014 at 04:55:40PM -0500, Don Zickus wrote: > > > > > > So here we mangle CPU3 in and lose the backtrace for cpu0, which might > > > > be the real interesting one .... > > > > > > Can you provide another dump? The hope is we get something not mangled? > > > > Working on it.. > > > > > The other option we have done in RHEL is panic the system and let kdump > > > capture the memory. Then we can analyze the vmcore for the stack trace > > > cpu0 stored in memory to get a rough idea where it might be if the cpu > > > isn't responding very well. > > > > I don't know if it's because of the debug options I typically run with, > > or that I'm perpetually cursed, but I've never managed to get kdump to > > do anything useful. (The last time I tried it was actively harmful in > > that not only did it fail to dump anything, it wedged the machine so > > it didn't reboot after panic).
Hi Dave Jones, Not being able to capture the dump I can understand but having wedged the machine so that it does not reboot after dump failure sounds bad. So you could not get machine to boot even after a power cycle? Would you remember what was failing. I am curious to know what did kdump do to make machine unbootable. > > > > Unless there's some magic step missing from the documentation at > > http://fedoraproject.org/wiki/How_to_use_kdump_to_debug_kernel_crashes > > then I'm not optimistic it'll be useful. I had a quick look at it and it basically looks fine. In fedora ideally it is just two steps process. - Reserve memory using crashkernel. Say crashkernel=160M - systemctl start kdump - Crash the system or wait for it to crash. So despite your bad experience in the past, I would encourage you to give it a try. > > Well, I don't know when the last time you ran it, but I know the RH kexec > folks have started pursuing a Fedora-first package patch rule a couple of > years ago to ensure Fedora had a working kexec/kdump solution. Yep, now we are putting everything in fedora first so it should be much better. Hard to say the same thing about driver authors. Sometimes they might have a driver working in rhel and not necessarily upstream. I am not sure if you ran into one of those issues. Also recently I have seen issues with graphics drivers too. > > As for the wedging part, it was a common problem to have the kernel hang > while trying to boot the second kernel (and before console output > happened). So the problem makes sense and is unfortunate. I would > encourage you to try again. :-) > > Though, it is transitioning to have the app built into the kernel to deal > with the whole secure boot thing, so that might be another can of worms. I doubt that secureboot bits will contribute to the failure. Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
