[lug] Re: Another question on X. displaying at two resolutions simultaneously?

[Phil Rasch]

Forgive me if I snip too much. 

On Tue, Dec 31, 2002 Michael J. Hammel wrote:
> What you need in hardware is video support for dual heads - two
> monitors, one video chipset (re: card).  If you're laptop (which is, if
> I remember the earlier messages, what you're trying this on) doesn't
> support this, you won't be able to do it.

And Ed Hill wrote:
> Flipping through "Fn-F7", my ThinkPad A22p running XFree 4.x will
> simultaneously display the same desktop image on both the LCD at
> 1600x1200 and on a projector at 1024x768.  Of course, it looks a lot
> nicer at the higher res, but the text is visible at the lower res using
> a sufficiently large font.  I've given a few presentations using it in
> exactly this manner.

I dont know if it qualifies as dual head, but the chip I am using
(savage s3) on an IBM T21 easily draws to both internal and external
monitors. And, as suggested by Ed, I can toggle between them. The
hardware switch Fn-F7 allows a write to either internal or external
monitor seperately, but it doesnt do them both. I had to download a small
standalone program (written by the guy responsible for the s3 driver
for the savage chipsets) called s3switch to drive them both
simultaneously. Maybe my problem is with that lousy chipset, or s3switch.

In the "both" mode, I can drive the monitors simultaneously with one
refresh rate. If I choose a configuration (via XF86Config-4)
that is relevant to the internal (1400x1050) resolution I cant synch
to the external monitor. If I choose a 1024x768 resolution then I can
draw to both monitors but either I write to a subset of the internal
screen or I let the BIOS stretch the image (which, as I said before
looks like crap.)

I would be curious to know see Ed's XF86Config-4 file (maybe offline?)
and know whether his BIOS is configured to allow the stretch option.

I did understand that xinerma "might" work with a single chipset, but
I have not been able to find a sample XF86Config-4 file, or a discussion in
a howto (and believe me I have looked) that provides an example of
this sort of thing. The two most illuminating discussions I found were

http://www.linuxgazette.com/issue82/ward.html
and
http://www.linuxdocs.org/HOWTOs/Xinerama-HOWTO.html

I figure that I can probably sort this out with a weeks worth of
work. I just didnt want to spend that kind of time on it and hoped you
guys had already solved the problem. In the meantime, I give talks
with both monitors set to 1024x768. It isnt that big a deal.

Thanks again.

Phil

-- 
Phil Rasch, Climate Modeling Section, National Center for Atmospheric Research
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