Apparently, though unproven, at 02:05 on Friday 04 February 2011, walt did opine thusly:
> On 02/03/2011 02:11 PM, Nikos Chantziaras wrote: > > On 02/03/2011 08:07 AM, Walter Dnes wrote: > >> Is there a way to have a real text console? I know that I can > >> have 2 X sessions on tty10 and tty11 with different resolutions, and > >> colour depths. Is there a way to set tty1..tty9 to 640x480 *IN TEXT > >> MODE*, so that lat1-?? fonts would look normal, without killing the > >> ability to have X run at 1920x1200? > > > > Note that the suggestion the others gave about disabling KMS is probably > > > >not what you need. Disabling KMS means that it will also be disabled for > >X11, not only for the framebuffer. As you can imagine this is a bad thing. > > I'm aware of KMS because of my experiments with the 'nouveau' driver, but > I still have no idea what KMS really does. > > In other words, I *cannot* imagine why disabling KMS is a bad thing, but I > would very much like to know :) Very short answer: Without KMS, changing video modes or changing from console to X requires a fantastically gigantic amount of swapping running code in and out, handing over control of the graphics hardware for one driver to another, and is a magnificent bug-injection mechanism. It's why it takes 2-3 seconds to switch from X to tty1 and why some hardware flickers like in banshee while doing it. KMS removes the need for the video driver to be aware of all the nonsense that requires. The driver no longer needs to get up close and personal with everything else the kernel is doing and make really sure it's timing is really right. Of course, the video driver has to support KMS for this to work. nVidia doesn't, nouveau does. In fact, nouveau *requires* KMS. It's such a good idea that the nouveau devs decided they were simply not going to support no-KMS. Disabling KMS (if it works with your hardware and drivers) in general is a bad idea as you lose all that nice KMS goodness. It's an especially bad idea with nouveau as the video hardware stops working at all. -- alan dot mckinnon at gmail dot com
