Dual Head, 8bpp and Centos 5 problem

[Alex Deucher]

On Mon, Jun 23, 2008 at 2:29 AM, Neil Thompson <abraxis at metroweb.co.za> wrote:
> On Fri, Jun 20, 2008 at 09:47:46AM -0400, Alex Deucher wrote:
>> On Fri, Jun 20, 2008 at 4:32 AM, Neil Thompson <abraxis at metroweb.co.za> wrote:
>> > Hi all,
>> >
>> > I have a legacy app which only runs in 8bpp that I have to
>> > get working on a CentOS 5 platform (xorg-x11-server-1.1.1 +
>> > Red Hat patches).  The app requires dual head, non cloned
>> > displays.
>> >
>> > The problem is that I cannot get X to come up in dual head
>> > mode when the DefaultDepth is set to 8.  Other depths (16 and
>> > 24) work fine, but when I change the DefaultDepth to 8, both
>> > screens display their built-in made change message, but only
>> > the primary (I assume) screen is initialised properly (the "X"
>> > comes up on it and I can move it around).  When I try to move
>> > the cursor to the other screen, it just disappears.  This is
>> > with the mga driver and a dual DVI card (hardware is fixed -
>> > I have to use it).
>>
>> My rusty recollection is that 8 bpp is not possible on crtc 2 (hw limitation).
>>
>
> That's just what I didn't need to hear :-{
>
> Do you have any recollection whether that's just on the mga driver, or just on
> dual dvi cards or anything like that?
>

This is a limitation of the mga hw.

> In other words, is there any way I can get 2 8-bit displays up?

It should be possible with other hw, but I doubt it gets tested often.

Alex