On 14/07/14 12:01, Anthony Wright wrote: > On 11/07/2014 13:17, David Vrabel wrote: >> On 11/07/14 12:27, Anthony Wright wrote: >>> On 11/07/2014 10:38, David Vrabel wrote: >>>> On 11/07/14 08:58, WANG Chao wrote: >>>>> On 07/10/14 at 11:11am, Anthony Wright wrote: >>>>>> Hi Chao, >>>>>> >>>>>> Thanks for looking at this. >>>>>> >>>>>> On 10/07/2014 08:47, WANG Chao wrote: >>>>>>> Hi, Anthony >>>>>>> >>>>>>> On 07/08/14 at 11:34am, Anthony Wright wrote: >>>>>>>> After successfully modifying kexec-tools to get it to load a crashkernel >>>>>>>> on a standard 32 bit linux 3.10.17 kernel, I tried to get it to load the >>>>>>>> same crashkernel on the same 32 bit linux kernel running under xen >>>>>>>> 4.4.0, but get the error "Cannot load <kernel-path>". >>>> Are you trying to do an in-guest kexec or are you trying to kexec from Xen? >>>> >>>> If it's the latter, it should just work with 32 and 64-bit images, Xen >>>> 4.4 and kexec-tools 2.0.5 or later. >>>> >>>> In-guest kexec doesn't work at all. >>>> >>>> David >>> I'm trying to do the kexec from within a 32 bit linux 3.10.17 Dom0 >>> running under a 64 bit xen 4.4.0. When you say 'guest', does that mean >>> DomU's or does that include Dom0 as well? If it includes Dom0 could you >>> point me at some documentation to explain how/if it's possible to set up >>> kexec/kdump for Dom0. >>> >>> I have a Dom0 kernel that's crashing infrequently. I can't reproduce it >>> easily and all the standard diagnostic techniques haven't been very >>> helpful. I'd hoped to generate a crashdump using kexec/kdump to help >>> diagnose the problem. >> I would suggest trying a Xen kexec and exec'ing your crashdump kernel >> (which will then be running on baremetal). >> >> You will need to reserve a region of memory for the crash kernel on the >> Xen command line (e.g., crashkernel=64M at 32M) and use kexec-tools 2.0.5 >> or later. >> >> We don't actually collect memory dumps from this environment (only basic >> PCPU/VCPU state, Xen/dom0 backtraces, and console logs) so I'm not sure >> what the status of tools for this are. Daniel Kiper might know. >> >> David > I had the 'crashkernel=128M' parameter on the Dom0 linux kernel cmdline. > Removing it from the Dom0 linux kernel command line and placing it on > the Xen command line changed things, but unfortunately it still doesn't > work. Try explicitly placing the crash region at a known address as I suggested above. > I get the error message 'failed to get crash region from hypervisor'. On > further investigation the call to xc_kexec_get_range() fails returning > -1 with an errno of 34 (Numerical result out of range). According to the > xen kexec documentation that I could find > (http://xenbits.xen.org/docs/4.4-testing/misc/kexec_and_kdump.txt), > there should be a 'Crash kernel' entry in /proc/iomem, however when I > look, no such entry exists. I do wonder if this is an error in the > documentation as I would expect a crashkernel= entry on the linux kernel > command line to create such an entry in /proc/iomem, but was suprised > when the documentation says the entry is created when you put > crashkernel= on the xen command line. 3.x kernels do not add entries into /proc/iomem. David
