Re: [Qemu-devel] [PATCH 6/6] kvm: qemu: fix vga screendump

[andrzej zaborowski]

2008/7/20 Anthony Liguori <address@hidden>:
> andrzej zaborowski wrote:
>>
>> 2008/7/17 Anthony Liguori <address@hidden>:
>>
>>>
>>> From: Avi Kivity <address@hidden>
>>> Commit 737d2050 ("Implement resolution switching in common console code")
>>> uses qemu_console_resize() instead of dpy_resize().  This means
>>> console->ds
>>> is examined instead of the VGA private ds, and the resize does not take
>>> place,
>>> leading to a segfault.
>>>
>>> Fix by modifying the DisplayState directly rather than swapping the
>>> pointer.
>>>
>>
>> The screen dumping is hacky but maybe it's a good idea to keep the
>> hacks local to hw/vga.c, with something like the following diff.  I
>> think we need to fix the screen dumping globally (some graphic cards
>> will need fixing too).
>>
>
> I agree the screen dumping is pretty hacky right now.  Instead of installing
> a new DisplayState, I've never understood why we can't just dump ds->data
> after an appropriate translation.

With -no-graphic there's no ds->data, or it can have lower bpp than
what's otherwise available.

>
> I think your patch looks better, but I can also code up a new screen dumping
> mechanism that doesn't take over DisplayState unless I'm missing something
> obvious.

It's worth a try, dumping ds->data is perhaps the way to go but
ds->depth is being set to 32bit and various video cards are optimised
on the assumption that ds->depth doesn't change, so maybe there should
be a notification callback.

Regards