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Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size |
Date: |
Mon, 12 May 2014 11:05:24 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
[adding libvirt]
On 05/09/2014 05:54 AM, Gerd Hoffmann wrote:
> Hi,
>
>> virt-manager/libvirt seems to default to 9 MByte of Vram for cirrus,
>> so this would break a lot of setups.
>
> It wouldn't. libvirt sticks that into the xml, but it doesn't set any
> qemu parameters. The libvirt parameter actually predates the qemu
> property for setting the size.
>
Then we should probably re-evaluate what libvirt does with the
parameters, which avoids breaking any guest that happens to be
pre-existing with the odd 9MB sizing in the XML.
>> Looking at datasheets on the web seems to say the chips actually went
>> down to 1 MB or less.
>
> I have my doubts we emulate that correctly (register telling the guest
> how much memory is actually there etc.). Also it is pretty much useless
> these days, even the 4MB imply serious constrains when FullHD displays
> are commonplace. Newer cirrus drivers such as the kernel's drm driver
> are specifically written to qemu's cirrus cards, I have my doubs that
> they are prepared to handle 1MB cirrus cards correctly.
>
> Bottom line: Allowing less than 4MB is asking for trouble for no good
> reason ;)
>
> cheers,
> Gerd
>
>
>
>
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size, Dr. David Alan Gilbert, 2014/05/09
Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size, Paolo Bonzini, 2014/05/09
Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size, Eric Blake, 2014/05/12