Forcing the vesa driver, how?

[Alex Deucher]

On Fri, Sep 10, 2010 at 12:22 AM, Gene Heskett <gene.heskett at gmail.com> wrote:
> Greetings all;
>
> I have now installed ubuntu-10.04 LTS on my old box that runs my milling
> machine, and its a disaster in terms of speed compared to 6.06.
>
> One thing that is a given is that I must use the vesa driver because all
> the others, including the radeon driver from the 10.04 install, do not seem
> to share interrupts well, or some such, causing 'unexpected realtime
> delays' of as much as 2 milliseconds, intolerable in a system driving
> stepper motors step by step.
>
> This application uses the RTAI facilities to run the machine in real time,
> and that works.  However my screen updates are at about 1.5 second
> intervals, and the position shown for the machines cutting tool is often as
> much as 5 seconds behind the machine.
>
> The vesa driver (its an ATI-9200SE card) will actually be considerably
> faster in this application.  Its 'realtime delays' are about 1/5th those of
> the radeon driver.
>
> So, since there is not an /etc/X11/xorg.conf file now, how do I force x to
> use the vesa driver at its optimum settings?
>

Add radeon.modeset=0 to your kernel command line in grub and set the
driver to vesa in the device section of your xorg.conf.  If you are
having problems with your radeon, it would be worthwhile to file a
bug:
https://bugs.freedesktop.org

Alex

> Thanks.
>
> --
> Cheers, Gene
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Luck, that's when preparation and opportunity meet.
>                -- P.E. Trudeau
>
> --
> Cheers, Gene
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Bus error -- driver executed.
>
>
> --
> Cheers, Gene
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If he had only learnt a little less, how infinitely better he might have
> taught much more!
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