Messages in this thread | | | Date | Wed, 19 Nov 2014 10:38:52 -0500 | From | Dave Jones <> | Subject | Re: frequent lockups in 3.18rc4 |
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On Wed, Nov 19, 2014 at 10:03:33AM -0500, Vivek Goyal wrote:
> 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.
Power cycling was fine, because then it booted into the non-kdump kernel. The issue was when I caused that kernel to panic, it would just sit there wedged, with no indication it even tried to switch to the kdump kernel.
> > > 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.
'the past' here, is two weeks ago, on Fedora 21.
But, since then, I've reinstalled that box with Fedora 20 because I didn't trust gcc 4.9, and on f20 things are actually even worse.
Right now it doesn't even create the image correctly:
dracut: *** Stripping files done *** dracut: *** Store current command line parameters *** dracut: *** Creating image file *** dracut: *** Creating image file done *** kdumpctl: cat: write error: Broken pipe kdumpctl: kexec: failed to load kdump kernel kdumpctl: Starting kdump: [FAILED]
It works if I run a Fedora kernel, but not with a self-built one. And there's zero information as to what I'm doing wrong.
I saw something similar on F21, got past it somehow a few weeks ago, but I can't remember what I had to do. Unfortunatly that was still fruitless as it didn't actually dump anything, leading to my frustration with the state of kdump.
I'll try again when I put F21 back on that machine, but I'm not particularly optimistic tbh.
Dave
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