Simulating a lower resolution on the OLPC XO Laptop

Sebastian Silva sebastian at
Tue Nov 25 10:44:18 EST 2008

Yes, quake 1 (which is GPL now, except for game data) is quite
playable at 640x480 but at 1200x900 it stutters and is no fun.

Yes, did I mention Quake runs? :-)
Scaling to lower resolution would be super cool indeed, for any
number of pseudo3d simulations and games, emulators and
legacy apps.


2008/11/25 Bert Freudenberg <bert at>:
> On 25.11.2008, at 11:57, Strider wrote:
>> Hi,
>> I have a XO Laptop which is a nice machine machine with a high res
>> display of 1200x900 pixels. The problem with this is that the laptop
>> isn't powerful enugh to handle fullscreen applications at this
>> resolution. If only the display could switch to a lower resolution
>> things would be much better but it seems that this laptop only
>> supports a single resolution.
>> So I was wondering if it would be possible of simulating lower res
>> at a low level, that is the xf86-video-geode driver.
>> I'm not an expert in video drivers but i imagine that there are
>> functions to request a pixel to be drawn on screen based on what's
>> in the video ram.
>> Now let's say that it's not one pixel but two that we put on screen,
>> and that we draw each lines two times. That would result in a
>> 600x450 resolution.
>> If we do the same thing but repating the operations three times , we
>> would have a 400x300 resolution.
>> Some emulators have a scale option to do such a thing and manage it
>> quite well, but if we had such an option in the video driver, the
>> result would be even faster !
>> So what do you think about this? Is it possible ?
> The Geode actually can do real upscaling (that is, scale multiple
> graphics resolutions to the panel resolution), it works fine on other
> machines and LCDs. But latest word is that this somehow interacts
> badly with our DCON, so no-one has gotten it to work correctly on the
> XO yet.
> There still may be hope, because the video upscaler can take RGB 5:6:5
> data, so in theory a lower-res 16 bpp frame buffer could be upscaled
> on-the-fly (and the upscaler does 30 fps easily). But I guess getting
> this to work would require a very determined X hacker ...
> - Bert -
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Sebastian Silva
Iniciativa FuenteLibre

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