Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked

[Gleb Natapov]

On Wed, Mar 14, 2012 at 03:07:46PM +0200, Avi Kivity wrote:
> On 03/14/2012 01:11 PM, Wen Congyang wrote:
> > > 
> > > 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?
> 
> Are you willing to try it out and see how complicated it really is?
> 
> While it's more complicated, it's also more flexible.  You can
> communicate the panic message, whether the guest is attempting a kdump
> and its own recovery or whether it wants the host to do it, etc., you
> can communicate less severe failures like oopses.
> 
hypercall can take arguments to achieve the same.

> > I think the other ones prefer to touch the hypervisor.
> 
> I understand the sentiment.  Your patches are simple and easy.  But my
> feeling is that the kernel has become too complicated already and I'm
> looking for ways to limit changes.
> 
Using virtio-serial will not reduce kernel complexity. Quite contrary
since code that will use virtio-serial will be more complicated.

--
                        Gleb.