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Re: [Qemu-devel] [PATCH v2 5/6] vga: Use linear mapping + dirty logging
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/6] vga: Use linear mapping + dirty logging in chain 4 memory access mode |
Date: |
Fri, 19 Aug 2011 08:19:35 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20110707 Thunderbird/5.0 |
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.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
[Qemu-devel] [PATCH v2 6/6] vga: Drop some unused fields, Jan Kiszka, 2011/08/17
[Qemu-devel] [PATCH v2 3/6] vmware-vga: Remove dead DIRECT_VRAM mode, Jan Kiszka, 2011/08/17