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Re: Hrumph!

Subject: Re: Hrumph!
From: Andreas Busse <>
Date: Sun, 3 Sep 1995 09:22:04 +0200
In-reply-to: <>
 > : Sure. Do it the Magnum/PICA way:
 > : 
 > :    if (boot_info.machtype == MACH_DESKSTATION_RPC44) {
 > :            ...
 > :            set rpc44 video information here
 > :            ...
 > :    } else
 > : #endif
 > Yes.  I did that, and the driver still isn't working, so I must have
 > done something wrong.

But you already had the console driver working for the dummy vmlinux,
right ? So you know where the video adapter lives, and that should
actually be sufficient for know.

 > : Also, make sure that you have a correct map0_table in kernel/head.S
 > : for the RPC44. Without a correct initial mapping nothing will work!
 > That's the problem, I think.  What is supposed to be mapped where?
 > I've stumbled around a bit trying to find it all, but more keeps
 > popping up.

For now, it should be enough to provide an empty table. However,
a mapping table must be there since the initialisation probably

 > Also, when MILO boots, is it in translated (using virutal addresses)
 > or untranslated mode?  Does the MIPS even have an untranslated mode?

Milo runs totally untranslated in KSEG1. The BIOS itself may translate
hardware addresses, though.

 > I know that in MILO the addresses 0x8000000 and 0xa0000000 start the
 > range of memory and the ISA bus is "overmapped" from 0xn00a0000 to
 > 0xn00fffff.  And that I/O ports start at 0xB0000000.
 > Hmmm, just got mail from Ralf suggesting I use tlbdump to see where
 > these guys are mapped and then put that into the map statement.  Hmmm,
 > I'll see if that works, but I thought I had this down :-(.

Well, if you still don't succeed, hardcode some video output
in head.S. This is what I've done for the Magnum and the Acer
to make sure that it gets thru the TLB initialization. Output
numbers or letter to the video ram (using hardcoded addresses)
after each code block in head.S. This way you can figure out 
where the problem is. Ugly, but works.


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