On Wed, Feb 29, 2012 at 12:08:19PM +0200, Avi Kivity wrote: > On 02/29/2012 12:05 PM, Gleb Natapov wrote: > > On Wed, Feb 29, 2012 at 12:00:41PM +0200, Avi Kivity wrote: > > > On 02/29/2012 11:55 AM, Gleb Natapov wrote: > > > > > > > > > > > > > > > > How about using a virtio-serial channel for this? You can transfer any > > > > > amount of information (including the dump itself). > > > > > > > > > Isn't it unreliable after the guest panicked? > > > > > > So is calling hypercalls, or dumping, or writing to the screen. Of > > > course calling a hypercall is simpler and so is more reliable. > > > > > Yes, crash can be so severe that it is not even detected by a kernel > > itself, so not OOPS message even printed. But in most cases if kernel is > > functional enough to print OOPS it is functional enough to call single > > hypercall instruction. > > Why not print the oops to virtio-serial? Or even just a regular serial > port? That's what bare metal does. > The more interface is complex the more chances it will fail during panic. Regular serial is likely more reliable than virtio-serial. Hypercall is likely more reliable than uart. On serial user can fake panic notification. Can this be problematic? > > > > Having special kdump > > > > kernel that transfers dump to a host via virtio-serial channel though > > > > sounds interesting. May be that's what you mean. > > > > > > Yes. The "panic, starting dump" signal should be initiated by the > > > panicking kernel though, in case the dump fails. > > > > > Then panic hypercall sounds like a reasonable solution. > > It is, but I'm trying to see if we can get away with doing nothing. > Fair enough. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
