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

[Jan Kiszka]

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?

>  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.

Jan

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