At 03/14/2012 06:48 PM, Avi Kivity Wrote: > On 03/14/2012 12:46 PM, Gleb Natapov wrote: >> On Wed, Mar 14, 2012 at 12:29:57PM +0200, Avi Kivity wrote: >>> On 03/14/2012 12:26 PM, Wen Congyang wrote: >>>>>> If so, is this channel visible to guest userspace? If the channle is visible to guest >>>>>> userspace, the program running in userspace may write the same message to the channel. >>>>>> >>>>> >>>>> Surely there's some kind of access control on channels. >>>> >>>> The virtio-serial depends on more things than touching the hypervisor. So I think touching >>>> the hypervisor is more reliable than using virtio-serial device, and it is very simple and >>>> easy to use. >>>> >>>> If we pass something from guest userspace to host, we can use virtio-serial. But If we pass >>>> something from guest kernelspace to host, I still prefer to touch the hypervisor. >>> >>> There's no argument that it's easier. My concern is different, we're >>> adding more and more stuff to the hypervisor because it's easier, which >>> bloats it. Every time we do it we add to compatibility and security >>> problems. >>> >>> The panic notification is *really* simple, so I don't expect it to cause >>> a lot of problems. But still, if it's possible not to change the >>> hypervisor, we must make an effort in that direction. >>> >> One more point against using virtio-serial is that it will be likely >> compiled as a module which means panic during early boot will not be >> reported. > > I don't think we want to use the driver. Instead, have a small piece of > code that resets the device and pushes out a string (the panic message?) > without any interrupts etc. > > It's still going to be less reliable than a hypercall, I agree. Do you still want to use complicated and less reliable way? I think the other ones prefer to touch the hypervisor. Thanks Wen Congyang -- 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
