Re: [linux-fbdev] Retrace

---------- Forwarded message ----------
Date: Mon, 7 Feb 2000 18:16:21 +0100 (CET)
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Petr Vandrovec <redacted>
Cc: Stefan Berndtsson <redacted>, linux-fbdev@vuser.vu.union.edu,
     Linux/PPC Development [off-list ref]
Subject: Re: [linux-fbdev] Retrace

On Tue, 1 Feb 2000, Petr Vandrovec wrote:

On  1 Feb 00 at 13:14, Stefan Berndtsson wrote:

quoted

quoted

  For now you have to do iopl(3); inb(0x3DA); iopl(0);... (you have to be
root to do this. As alternative on matroxfb, you can mmap accelerator
space and read register at offset 0x1FDA in this space. It contains
same value as port 0x3DA does, but for mmapping /dev/fbX you do not
need root rights.

You (or anyone really) wouldn't happen to know how to access 0x3da, or
whatever equivalent method there is, on an ATI Rage Pro LT, running
on PPC?

I believe that on PReP it is byte in memory (/dev/mem) at physical address
0x800003DA, but Geert probably knows more details (maybe there is even

First you have to mmap() ISA I/O space using /dev/mem and put the mapped
address in isa_io_base. Then you can use inb() and friends (cfr.
include/asm-ppc/io.h).

And now the bad news: the address you have to mmap() depends on the machine
type :-(

/dev/ioport on PPC).

Nope. But perhaps we should remove the #if !defined(CONFIG_PPC) around the
port operations in drivers/char/mem.c?

Gr{oetje,eeting}s,
--
Geert Uytterhoeven -- Linux/{m68k~Amiga,PPC~CHRP} -- geert@linux-m68k.org

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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On Tue, 08 Feb 2000, Geert Uytterhoeven wrote:

Nope. But perhaps we should remove the #if !defined(CONFIG_PPC) around the
port operations in drivers/char/mem.c?

Sounds like a good way to get machine checks to me.  But then only root can
do it so maybe it doesn't matter.

Paul.

--
Paul Mackerras, Senior Open Source Researcher, Linuxcare, Inc.
+61 2 6262 8990 tel, +61 2 6262 8991 fax
paulus@linuxcare.com.au, http://www.linuxcare.com.au/
Linuxcare.  Support for the revolution.

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