Subject: XZ graphics specs...

From: John Michael Clemens <[email-masked]>
Date: Thu, 13 Jan 2000 14:55:55 -0500 (EST)

I too have been working on getting my Indigo2 to boot... and now that I
seem to have mine working as well, I can move on to actually helping.  

Now that the EISA stuff is in the kernel, should it now be possible to
write video drivers (framebuffers, console drivers, X servers) for the
Indigo2's???.. Having said that, I have GR3-Elan (XZ) graphics on mine,
can someone tell me where I can find the specs to start hacking up at
least a framebuffer for this?  techpubs.sgi.com doesn't seem to have much
info... is this info even availabe to those outside for SGI?

Also, can someone warn me about what dangers (if any) there will be to my
*VERY NICE* Sony GDM17E21 if I start playing around with video timings and
suff?  The last thing I need is to kill my only really nice monitor that I
use for my PC's and my SGI...

Any info would be MUCH appreciated.
john.c

- --
/* John Clemens     http://www.rpi.edu/~clemej _/ "I Hate Quotes"       */
/* ICQ: 7175925     [email-masked]           _/    -- Samuel L. Clemens */ 
/* RPI Comp. Eng. 2000, Linux Parallel/Network/OS/Driver Specialist     */

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From: "William J. Earl" <[email-masked]>
Date: Thu, 13 Jan 2000 15:32:30 -0800 (PST)

> info... is this info even availabe to those outside for SGI?

       Basically, XZ hardware documentation is not available outside SGI.
We have agreement inside SGI to provide some information, if a volunteer
inside SGI appears to track it down, but no volunteer so far.  The problem
is that the hardware interface is quite complex, and some of what one
thinks of as hardware is really firmware, a basic version of which is
downloaded by the PROM at startup time.  An X server could rely on the
PROM-loaded firmware, but it still takes quite a bit of code to set up
the hardware.  Note that XZ, like Newport graphics on Indy, does not
have a CPU-addressable frame buffer, so you have to use the rendering interface.

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From: John Michael Clemens <[email-masked]>
Date: Thu, 13 Jan 2000 22:56:25 -0500 (EST)

On Thu, 13 Jan 2000, William J. Earl wrote:

> inside SGI appears to track it down, but no volunteer so far.  

:), I kindav figured as much, but it never hurts to ask.  I'd
volunteer to come work at SGI to do it to, but my resume I sent there
seems to be .. umm.. ignored.

> The problem
> the hardware.  

Would there be enough in this firmware to do a basic text console?  even
that would be better than soldering together a serial cable to run over
Minicom.

> Note that XZ, like Newport graphics on Indy, does not

Would this be at all analgous to the code I saw poking around the Xfree
tree once that implemented a server for the Voodoo(2) 3D-only cards?
For that matter, how closely related are the XZ and XL?

thanks for the info.

on an unrelated note: I'm slightly confused... is the R4400-Indigo2 32 or
64 bit?

thanks again,
john.c

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From: "Soren S. Jorvang" <[email-masked]>
Date: Fri, 14 Jan 2000 05:56:13 +0100

> that would be better than soldering together a serial cable to run over

You can always use the PROM callbacks for that.

-- 
Soren

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From: Geert Uytterhoeven <[email-masked]>
Date: Fri, 14 Jan 2000 09:46:19 +0100 (CET)

> have a CPU-addressable frame buffer, so you have to use the rendering interface.

You can still write a frame buffer device for it, but you can't export the
frame buffer to userspace (smem_start and smem_len == 0). Just make sure you
fill in your own drawing routines in display->dispsw.

Gr{oetje,eeting}s,
--
Geert Uytterhoeven -- Linux/{m68k~Amiga,PPC~CHRP} -- [email-masked]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

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From: James A Simmons <[email-masked]>
Date: Fri, 14 Jan 2000 09:40:14 -0500 (EST)

> fill in your own drawing routines in display->dispsw.

In the next few days I will be introducing fbcon-accel.c which are a set
of console functions wrapped around the accel features of a card. I hope
to have this go into the 2.3.x kernels soon.

Codito, ergo sum - "I code, therefore I am"
James Simmons                                                      (o_
fbdev/gfx developer                                      (o_  (o_ //\
http://www.linux-fbdev.org                              (/)_ (/)_ V_/_
http://linuxgfx.sourceforge.net

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From: Ralf Baechle <[email-masked]>
Date: Fri, 14 Jan 2000 11:44:30 +0100

> You can always use the PROM callbacks for that.

In theory yes.  In practice all firmware that I've seen so far seems to
be rather fragile and for some systems also very performance limited as
it's running from uncached memory (veeeerry slooow) or at times even
from 8-bit wide PROMs which is so slow that it blows every meassure for
slowness.  Not to mention other problems.  So this should really be
considered a better than nothing solution.

That being said, Ulf Carlsson has implemented a PROM console which is
in the CVS archive.  Try it, I'm interested in reports.

  Ralf

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From: "William J. Earl" <[email-masked]>
Date: Fri, 14 Jan 2000 21:28:02 -0800 (PST)

> in the CVS archive.  Try it, I'm interested in reports.

      On some platforms the PROM code is actually copied to main memory
and executed (cached) from there.  If I remember correctly, O2 works that
way.  Indy is probably in the slow (possibly very slow) category.

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From: Ralf Baechle <[email-masked]>
Date: Sat, 15 Jan 2000 12:47:26 +0100

> way.  Indy is probably in the slow (possibly very slow) category.

Running from a PROM would explain why the Indy firmware crashes with
enabled L2 caches - the circuitry just wasn't designed to deal with the
type of access cycles (bursts?) as used by the l2 cache controller.
No major problem in practice.

  Ralf

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From: John Michael Clemens <[email-masked]>
Date: Sat, 15 Jan 2000 10:36:07 -0500 (EST)

FWIW,

I tried the PROM console last nigth and it was a no-go.  kernel downloaded
from the bootp server and just sat there, nothing on console, nothing on
serial.  When I hit CTRL-C to get a prompt back, however, I discovered
that my font had changed to black-on-black, so SOMETHING happened.

This is on an Indigo2-R4400, which boots just fine over the serial
console, and CONFIG_SGI_PROM_CONSOLE asserted (after a little modification
to the config.in to take it OUT of the DEC only section, ala what Mr.
Weaver mentioned earlier, and the extraneous "NULL" removed from
setup_console in arch/mips/sgi/setup.c) 

john.c

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From: Ralf Baechle <[email-masked]>
Date: Sun, 16 Jan 2000 01:57:26 +0100

> setup_console in arch/mips/sgi/setup.c) 

Ok, something for the to-do list.  Unfortunately at the bottom of the
list ...

  Ralf