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Date: Mon, 10 Dec 2007 20:03:35 +0100
From: "andrzej zaborowski" <balrogg@gmail.com>
Subject: Re: [Qemu-devel] [PATCH] ioemu/qemu vga: save and restore vram buffer
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To: qemu-devel@nongnu.org
Cc: xen-devel@lists.xensource.com

On 10/12/2007, Ian Jackson <Ian.Jackson@eu.citrix.com> wrote:
> The existing stdvga driver from xen-unstable tools/ioemu/hw/vga* does
> not save the emulated VGA memory contents.  The symptoms include video
> malfunction after restore, including black screen (which can often be
> fixed by asking the guest to redraw) but also missing font setup etc.
> The attached patch fixes this by saving the entire VGA memory buffer,
> just like the Xen ioemu Cirrus emulator does.

Sounds reasonable.

>
> I have reinterpreted the `is_vbe' byte, which is related to
> CONFIG_BOCHS_VBE, as a general flags word.  This enables my code to
> allow old images to be restored (albeit with loss of VGA memory), by
> using another bit in that word to indicate whether the VGA memory dump
> is present.

You can use the version_id parameter for that. Increase the value
passed to register_savevm and load the vram only if version_id >= 2.

Regards