Re: [Qemu-devel] [PATCH v2 5/6] vga: Use linear mapping + dirty logging in chain 4 memory access mode

[Avi Kivity]

On 08/18/2011 03:26 PM, Jan Kiszka wrote:
> On 2011-08-17 16:48, Avi Kivity wrote:
> >  On 08/17/2011 04:38 PM, Avi Kivity wrote:
> >>
> >>  The mmio code has
> >>
> >>              s->plane_updated |= mask; /* only used to detect font
> >>  change */
> >>
> >>  aren't we losing it?  we could easily recover it via dirty logging.
> >>
>
> Yes, I forgot to forward-port plane_updated = 0xf from v1 of the patch.
>
> >
> >  We can't really recover it.
>
> I don't see yet why we should not if we simply enforce a full update.
> Can you elaborate?

If we go for a full update we might as well disable dirty logging entirely.

> >   So I think we need to restrict the
> >  optimization to graphic mode.
> >
> >  Is grub using text mode or graphic mode?
> >
> >  If it's using text mode, it may be faster to compare the font plane to a
> >  snapshot from the last redraw than to take an exit.
>
> I wasn't optimizing for text mode here, it's just a side effect if it
> happens to benefit from it as well. I could exclude it, but only if
> really needed.

Ok, so grub is using graphic mode?


We'll need to force full updates in text mode then.

--
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