From: Gerd Hoffmann <kraxel@redhat.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: weidong.huang@huawei.com, mst@redhat.com, qemu-devel@nongnu.org,
arei.gonglei@huawei.com, pbonzini@redhat.com, afaerber@suse.de
Subject: Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size
Date: Fri, 09 May 2014 13:54:39 +0200 [thread overview]
Message-ID: <1399636479.5213.56.camel@nilsson.home.kraxel.org> (raw)
In-Reply-To: <20140509111807.GA22335@work-vm>
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.
> 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
next prev parent reply other threads:[~2014-05-09 11:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-09 10:21 [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size arei.gonglei
2014-05-09 10:31 ` [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size [checkpatch false positive?] Gerd Hoffmann
2014-05-09 10:40 ` Gonglei (Arei)
2014-05-09 10:54 ` Gerd Hoffmann
2014-05-09 10:59 ` Gonglei (Arei)
2014-05-09 11:53 ` [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size Andreas Färber
2014-05-09 11:18 ` Dr. David Alan Gilbert
2014-05-09 11:50 ` Paolo Bonzini
2014-05-09 11:54 ` Gerd Hoffmann [this message]
2014-05-09 12:02 ` Dr. David Alan Gilbert
2014-05-12 17:05 ` Eric Blake
2014-05-12 17:53 ` Andreas Färber
2014-05-12 17:03 ` Eric Blake
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