On 04/11/2012 01:12 PM, zhangyanfei wrote: > > > >> TODO: > >> 1. In kexec-tools, get VMCSINFO via sysfs and dump it as note information > >> into vmcore. > >> 2. Dump VMCS region of each guest vcpu and VMCSINFO into qemu-process > >> core file. To do this, we will modify kernel core dumper, gdb gcore > >> and crash gcore. > > > > > > Seems excessive. Why do you want vmcs information in qemu cores? A > > qemu crash is very rarely related to kvm, let alone the vmcs. I > > understand that you may want it in a kernel core dump, though I've never > > needed to myself. Can you outline a case where this data was needed? > > > > If a qemu process comes to a fatal error that causes itself to be core dumped > by kernel, the running guest based on the qemu process will be included in that > qemu core file. But with no vmcsinfo information in qemu core file, we could not > get the guest's states(registers' values), then we could not make a complete > guest vmcore. We can't anyway. Many registers (GPRs except RSP, fpu) are not stored in the VMCS, but in kvm data structures. So for this case we'd want a kvm callback to execute (that would make it work cross vendor, too). > > >> 3. Dump guest image from the qemu-process core file into a vmcore. > > > > For this perhaps a different approach is better - modify the core dumper > > to call kvm to extract the relevant vmcs information into an elf note. > > This way there is no need to reconstruct the guest data from the > > offsets. It's also more reliable, since vmread can access cached fields > > that direct memory access cannot. > > > > Does this approach is a replacement for TODO 2 ? That is to say, when generating > a qemu core by kernel core dumper, we could call kvm to extract the relevant vmcs > information into an elf note instead of VMCSINFO and the whole vmcs regions. Yes. I'm not convinced it's important though. -- error compiling committee.c: too many arguments to function
