On Thu, Jul 24, 2008 at 4:39 AM, Alexander Graf <agraf at suse.de> wrote: > > On Jul 24, 2008, at 2:13 AM, Mike Snitzer wrote: > >> On Sat, Jul 5, 2008 at 7:20 AM, Avi Kivity <avi at qumranet.com> wrote: >>> >>> Mike Snitzer wrote: >>>> >>>> My host is x86_64 RHEL5U1 running 2.6.25.4 with kvm-70 (kvm-intel). >>>> >>>> When I configure kdump in the guest (running 2.6.22.19) and force a >>>> crash (with 'echo c > /proc/sysrq-trigger) kexec boots the kdump >>>> kernel but then the kernel hangs (before it gets to /sbin/init et al). >>>> On the host, the associated qemu is consuming 100% cpu. >>>> >>>> I really need to be able to collect vmcores from my kvm guests. So >>>> far I can't (on raw hardware all works fine). >>>> >>>> >>> >>> I've tested this a while ago and it worked (though I tested regular >>> kexecs, >>> not crashes); this may be a regression. >>> >>> Please run kvm_stat to see what's happening at the time of the crash. >> >> OK, I can look into kvm_stat but I just discovered that just having >> kvm-intel and kvm loaded into my 2.6.22.19 kernel actually prevents > > Is 2.6.22.19 your host or your guest kernel? It's very unlikely that you > loaded kvm modules in the guest. Correct, 2.6.22.19 is my host kernel. >> the host from being able to kexec/kdump too!? I didn't have any >> guests running (only the kvm modules were loaded). As soon as I >> unloaded the kvm modules kdump worked as expected. >> >> Something about kvm is completely breaking kexec/kdump on both the >> host and guest kernels. > > I guess the kexec people would be pretty interested in this as well, so I'll > just CC them for now. > As you're stating that the host kernel breaks with kvm modules loaded, maybe > someone there could give a hint. OK, I can try using a newer kernel on the host too (e.g. 2.6.25.x) to see how kexec/kdump of the host fairs when kvm modules are loaded. On the guest side of things, as I mentioned in my original post, kexec/kdump wouldn't work within a 2.6.22.19 guest with the host running 2.6.25.4 (with kvm-70). Mike
