On Fri, Jul 19, 2013 at 08:32:35PM +0200, Daniel Kiper wrote: > On Fri, Jul 19, 2013 at 08:12:43AM -0700, Greg KH wrote: > > On Fri, Jul 19, 2013 at 03:18:19PM +0200, Daniel Kiper wrote: > > > > support is "easy" after your patches go in, is that because Dom0 needs > > > > to support this, or is it something specific to only domU? > > > > > > In case of domU we should consider following cases: > > > - PV guests: there is no support for kexec at this time; > > > Once I wrote an implementatation for that type of guests > > > for one company but according to our agreement I could not > > > publish this code; However, I could use it as a base for > > > publicly available kexec implementation; Currently, I do > > > not have any plans to work on this due to some more important > > > stuff to do; However, question about kexec support for PV > > > guests is raised from time to time and maybe this issue > > > will be much more important than others once, > > > - HVM guests: kexec should work without any issue, > > > - PVonHVM guests: IIRC, there were some issues with PV > > > drivers but they were fixed some time ago by patches > > > posted by Olaf Hering, > > > - PVH guests: those type of guests are not available in Xen > > > current releases yet; However, Konrad Wilk done some preliminary > > > work on kexec support but there are still some issues to resolve. > > > > > > I do not know what are you trying to do but if you would like > > > to get some crash dumps there is also another solution to that. > > > You could use xm/xl dump-core from Dom0 to get dumps of domU memory. > > > > As Brandon said, we were trying to use kexec in a PV guest in domU to > > run another kernel. I had assumed this wouldn't need support from dom0. > > You are right. > > > As you have implemented this in the past, did you need to change dom0 in > > order to achieve this, and if so, why? > > It was strong requirement to not change anything in hypervisor or dom0. > I succeeded to do that but it requires changes in kernel and kexec-tools. > > > The errors that the kexec tools seem to run into is finding the memory > > to place the new kernel into, is that just an issue that PV guests > > aren't given enough kernel memory in which to replicate themselves from > > dom0? > > There are a lot of differences between baremetal machines and PV guests. > For example you are not able to do identity mapping per se in PV guests. > Arguments to new kernel are passed in completely different way. etc.
Ok, thanks for confirming that it is possible, but doesn't currently work for pv guests. greg k-h _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
