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Re: Good news: no more begging for HW

To: Miguel de Icaza <miguel@nuclecu.unam.mx>
Subject: Re: Good news: no more begging for HW
From: offer@sgi.com (richard offer)
Date: Tue, 17 Jun 1997 10:53:12 -0700
Cc: linux@morgaine.engr.sgi.com
In-reply-to: Miguel de Icaza <miguel@nuclecu.unam.mx> "Re: Good news: no more begging for HW" (Jun 17, 12:10pm)
References: <199706171710.MAA15321@athena.nuclecu.unam.mx>
Sender: owner-linux@cthulhu.engr.sgi.com
* $ from miguel@nuclecu.unam.mx at "17-Jun:12:10pm" | sed "1,$s/^/* /"
*
*
*
* > If someone takes the server, I'll try and get the clients libraries done
* > (assuming that I can get remote access to a box).
*
* I was interested in working on the X server for the SGI.  I already
* did that for the Linux/SPARC, and I had a couple of questions to make,
* so this seems like a good time to ask them (please note that I haven't
* actually traced my SGI X server to see what it does).

The questions are good, but I'm not the person who can answer them, me I'm a
Motif hacker, anything at a level lower than Xt is akin to assembler for me.

So with that in mind take the rest with a pinch of salt.

*
* 1. On the SPARC, the X server mmap()s the frame buffer into its
*    address space and uses a couple of ioctls to talk with the kernel
*    (to ask the kernel to change the palette and the hardware cursor,
*    on later versions, with got rid of that, and we just poked at the
*    frame buffer control registers from the X server).
*
*    How does this work on the SGI?  Is the video card just a thing that
*    can be mapped into the X server address space?
*
*    If this is the case, getting the X11R6 server to work will just take
*    a couple of days of coding.
*
*
* 2. What kind of acceleration features are available on the SGI
*    machines?  The X11R6 server has hooks for different set of
*    features, so for example, bitblit can be easily hacked into the X
*    server.
*
*    But I imagine the SGI has more acceleration features that I can
*    dream of.

The problem is that (I think) we have so many graphics cards that its done
differently in every one (some cards are simple frame buffers (8/24bit), then
there are some with multiple GE, oh and we also have extra visuals for overlay
and pop-ups.

The O2 has no graphics memory, everything is done in main memory.

*
*
* 3. How does OpenGL work on the SGIs?  Is the OpenGL engine embedded in
*    the X server, or it is something that is present on the video card?
*
*    I looked yesterday at a program called glxinfo, which led me to
*    believe that applications may have some of the GL code linked in
*    trough the libraries and the other part resides on the X server.

Both :-) We don't do things the way easy here.

The is a GLX extension in the X server which allows GL to run in an X window.

There is also I think a DSO that holds the hardware specific GL calls.

*
*    So, in this case, what are the specs for what needs to be on the X
*    server to be able to run OpenGL applications.
*
*
* 4. Would it be possible for a free software company to redistribute
*    the SGI's X server?  In that case, we could concentrate on getting
*    the IRIX emulation as good as possible and just use the SGI X
*    server and let Red Hat/Debian/GNU ship the cd with that binary.

This would be my preferred solution, but I've had many an argument on this
subject that I felt very dubious about bringing it up again.

To me the quickest (and the best) way of getting an X server would be if we
could simply port the existing Irix X server to Linux/SGI. My suggestion would
be, now that we have backing for hardware to get official backing for software.
I don't think we should neccesarrily release the source code for the ddx part
of the X server to the public, but we should at least be able to get backing to
release .o files so the user could re-link the X server if they needed to (Sun
have done this before).

*
*
* Cheers,
* Miguel.
*
*


richard


-----------------------------------------------------------------------
Richard M. Offer        Widget FAQ --> http://reality.sgi.com/widgetFAQ
MTS-Core Design (Motif)
___________________________________________http://reality.sgi.com/offer


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