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Re: [Linux-fbdev-devel] Reading the EDID block for x86 machines
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From: Jon S. <jon...@ya...> - 2003-03-17 19:33:39
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--- Antonino Daplas <ad...@po...> wrote:
> You're talking about other device's expansion ROM's.
> VGA ROM's,
> especially for the x86, are an exception and has to
> be always mapped at
> c000:0000.
Reboot and add pci=rom (case sensitive) to your kernel
parameters. That will show you where the video ROMs
are really located.
My x86 PC's boot video ROM is located at dd000000 not
C00000. C00000 is only a copy of the ROM in RAM.
01:00.0 VGA compatible controller: ATI Technologies
Inc Radeon R250 If [Radeon 9
000] (rev 01) (prog-if 00 [VGA])
Subsystem: C.P. Technology Co. Ltd: Unknown
device 2039
Flags: stepping, 66Mhz, medium devsel, IRQ 5
Memory at d0000000 (32-bit, prefetchable)
[disabled] [size=64M]
I/O ports at c000 [disabled] [size=256]
Memory at de000000 (32-bit, non-prefetchable)
[disabled] [size=64K]
Expansion ROM at dd000000 [size=128K]
Capabilities: [58] AGP version 2.0
Capabilities: [50] Power Management version 2
The ROM on my other video card is located here:
00:0b.0 VGA compatible controller: ATI Technologies
Inc Rage 128 PD/PRO TMDS (pr
og-if 00 [VGA])
Subsystem: ATI Technologies Inc Rage 128 AIW
Flags: bus master, stepping, medium devsel,
latency 32, IRQ 10
Memory at d8000000 (32-bit, prefetchable)
[size=64M]
I/O ports at e400 [size=256]
Memory at df000000 (32-bit, non-prefetchable)
[size=16K]
Expansion ROM at 20060000 [size=128K]
Capabilities: [5c] Power Management version 2
> Remember, ROM's are supposed to be read-only, so
> even if they are
> shadowed, the BIOS write protects it.
How is this write protection being achieved? Is it
done via manipulation of the processor descriptor
tables; if so just undo it.
=====
Jon Smirl
jon...@ya...
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