Re: [Qemu-devel] [PATCH 1/2] Move graphic-related coalesced MMIO flushes to affected device models

[Avi Kivity]

On 10/18/2011 06:49 PM, Jan Kiszka wrote:
> On 2011-10-18 18:40, Avi Kivity wrote:
> > On 10/18/2011 04:30 PM, Avi Kivity wrote:
> >> This takes a while to reproduce, let me talk to gdb for a bit.
> >>
> > 
> > a vcpu exit causes kvm_flush_coalesced_mmio_buffer() to run, which does
> > a bitblt, which is cirrus_do_copy(), which goes to vga_hw_update, which
>
> Why does it have to do vga_hw_update? Why can't it set some flag for the
> next requested screen update or so? Just thinking, haven't looked at the
> code yet.

Maybe it's a remnant from the days where it asked the host hardware to
do the blt.

> Do you think that only cirrus is affected by this pattern?

It's also possible for hotunplug:

- hotunplug
- unregister coalesced regions
- flush mmios
- call back into same device

-- 
error compiling committee.c: too many arguments to function