Widescreen Optimum Use

Lennart Sorensen lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org
Tue Dec 15 18:51:51 UTC 2009


On Tue, Dec 15, 2009 at 01:49:13PM -0500, D. Hugh Redelmeier wrote:
> Some drivers can only use resolutions that are supported by the BIOS.
> I *think* "kernel mode setting" can get arround this.  KMS is a
> feature being pushed into as many drivers as possible (with sometimes
> painful failures).
> 
> Non-kernel modesetting was done (if I understand this correctly) by X
> using an i386 emulator running BIOS modesetting code carefully.
> That's why only BIOS-supported resolutions could be implemented.

If the driver knows the video chip well enough it can set the resolution
itself.  Only vesa should have any reason to use the BIOS for modes
anymore.  Of course some chips simply can't generate some resolutions.

> But I may have this wrong.
> 
> Certainly the VGA driver (the generic fallback when X does not know
> how to run the particular video chips) is limited to BIOS-supported
> resolutions.

Of course.  It is generic.

> My KVMs are old enough that the don't pass DDC/EDID.  They don't lie.

Not passing it is pretty close to lying, and pretty pathetic to not
support something that was common on monitors in 1995.  When did you
buy these things?

> Interestingly, this has exposed a bug in the Savage driver.
> https://bugzilla.redhat.com/show_bug.cgi?id=491488

-- 
Len Sorensen
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