On 23/11/2012 01:38, H. Peter Anvin wrote: > I still don't really get why it can't be isolated from dom0, which would make more sense to me, even for a Xen crash. > The crash region (as specified by crashkernel= on the Xen command line) is isolated from dom0. dom0 (using the kexec utility etc) has the task of locating the Xen crash notes (using the kexec hypercall interface), constructing a binary blob containing kernel, initram and gubbins, and asking Xen to put this blob in the crash region (again, using the kexec hypercall interface). I do not see how this is very much different from the native case currently (although please correct me if I am misinformed). Linux has extra work to do by populating /proc/iomem with the Xen crash regions boot (so the kexec utility can reference their physical addresses when constructing the blob), and should just act as a conduit between the kexec system call and the kexec hypercall to load the blob. For within-guest kexec/kdump functionality, I agree that it is barking mad. However, we do see cloud operators interested in the idea so VM administrators can look after their crashes themselves. ~Andrew
