Re: radeon-pre-2

[Vladimir Dergachev <volodya@mindspring.com>]

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On Sun, 12 Sep 2004, Michel [ISO-8859-1] Dänzer wrote:

> On Sun, 2004-09-12 at 20:45 -0400, Vladimir Dergachev wrote:
>>
>> On Sun, 12 Sep 2004, Michel [ISO-8859-1] Dnzer wrote:
>>
>>> On Sun, 2004-09-12 at 23:42 +0100, Dave Airlie wrote:
>>>>
>>>> I think yourself and Linus's ideas for a locking scheme look good, I also
>>>> know they won't please Jon too much as he can see where the potential
>>>> ineffecienes with saving/restore card state on driver swap are, especailly
>>>> on running fbcon and X on a dual-head card with different users.
>>>
>>> Frankly, I don't understand the fuss about that. When you run a 3D
>>> client on X today, 3D client and X server share the accelerator with
>>> this scheme, and as imperfect as it is, it seems to do a pretty good job
>>> in my experience.
>>
>> Not that good - try dragging something while a DVD video is playing.
>
> What are you getting at?

The overlay window is currently using part of what is being proposed by
"multiple drivers" proponents. It has to make engine queiscent so it can 
write data directly to the video memory. It does *not* have to save the 
state.

So, as Jon rightly points out the "multiple drivers" scheme only makes 
sense in the current usage patter - you either use X or framebuffer, never 
both at the same time and you consider a few seconds per switch normal.
(Not that it actually has to take few seconds, I am just pointing out the 
the expectations are well below what we do now)

However, if we want the switch from X to framebuffer to be as fast as 
switching between different text consoles (assuming they have the same 
resolution) and if we want to be able to run different Xservers on 
different consoles or Xserver+framebuffer combinations Jon's proposal 
wins.

                        best

                           Vladimir Dergachev

>
>
> -- 
> Earthling Michel Dänzer      |     Debian (powerpc), X and DRI developer
> Libre software enthusiast    |   http://svcs.affero.net/rm.php?r=daenzer
>