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Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 1
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest |
Date: |
Fri, 26 Jul 2013 12:19:16 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130621 Thunderbird/17.0.7 |
On 07/26/13 12:02, Andreas Färber wrote:
> Am 26.07.2013 08:41, schrieb Gonglei (Arei):
>>> -----Original Message-----
>>> From: Anthony Liguori [mailto:address@hidden
>>> Sent: Friday, July 26, 2013 11:21 AM
>>> To: Gonglei (Arei)
>>> Cc: address@hidden; address@hidden; Hanweidong;
>>> Luonengjun; Huangweidong (Hardware)
>>> Subject: Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen
>>> last 13s or so for windows XP guest
>>>
>>> On Thu, Jul 25, 2013 at 10:08 PM, Gonglei (Arei)
>>> <address@hidden> wrote:
>>>> 3. Why does the traditional qemu has no blank screen problem on cirrus VGA
>>> emulation ?
>>>
>>> This is one of the few cases where TCG is actually faster than KVM or
>>> Xen. In TCG, an MMIO exit is converted to a function call. OTOH,
>>> even with KVM, an MMIO exit is at least a couples thousand cycles.
>>> It's worse with Xen because dom0 has to be scheduled.
>>
>> Perhaps I did not express clearly what I mean at #3.
>> I don't understand why the qemu-dm(qemu-0.10.2) works well
>> but the upstream qemu(begin with qemu-0.14) is not for the
>> same windows XP guest image in cirrus vga emulation. Does
>> the cirrus vga emulation have some differences between
>> qemu-dm and unstream qemu ?
>
> I don't know about qemu-dm, but QEMU switched from a home-grown pixel
> handling to pixman library sometime around 1.4. CC'ing Gerd.
0.14 != 1.4 ;)
Also pixman isn't used everywhere, there is still home-grown pixel
handling code in qemu. I often replace it when I touch it for some
reason, but we are far away from a full-pixman qemu. The cirrus blit
ops havn't been touched btw, it's still the old code.
Maybe the xen guys did some optimizations in qemu-dm which where not
merged upstream. Try asking @ xen-devel.
Beside that the standard vga usually is the better choice anyway as it
supports more video memory and higher resolutions than cirrus.
cheers,
Gerd
- Re: [Qemu-devel] [Xen-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, (continued)
Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Anthony Liguori, 2013/07/25
- Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Gonglei (Arei), 2013/07/25
- Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Anthony Liguori, 2013/07/25
- Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Gonglei (Arei), 2013/07/26
- Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Andreas Färber, 2013/07/26
- Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest,
Gerd Hoffmann <=
- Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Andreas Färber, 2013/07/26
- Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Gonglei (Arei), 2013/07/27
- Re: [Qemu-devel] [Xen-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Pasi Kärkkäinen, 2013/07/27
- Re: [Qemu-devel] [Xen-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Gonglei (Arei), 2013/07/29
- Re: [Qemu-devel] [Xen-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Pasi Kärkkäinen, 2013/07/29
- Re: [Qemu-devel] [Xen-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Gonglei (Arei), 2013/07/29
Re: [Qemu-devel] [Xen-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Fabio Fantoni, 2013/07/26
Re: [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest, Gonglei (Arei), 2013/07/26