From: peter@plan9.com peter@plan9.com
Subject: Memory on NeXT
Date: Thu, 5 Oct 1995 11:27:00 -0400 [thread overview]
Message-ID: <19951005152700.cMcibCxBiBElJU4P-l8pxwn8nKtU2BIWNqANo7237Z0@z> (raw)
> It seems that Plan 9 only recognizes the first two bank of NeXT
> memory. At boot time, the message:
>
> bank 0: 4M bank 1: 4M
> appears on the screen and that's exact memory I have on the first two
> simm slots. However, there are 16 simm slot on a Cube and I have
totally
> 40 MB on the mother board.
> When I look at the source, the conf structure seems to only use
the first
> two banks and compute everything base on the two bank of memory.
>Is there a way I can make Plan 9 recognize the rest of the memory banks?
> Ta-Wei Li
The architecture independent code for Plan 9 implements two memory
banks, and while this can be changed for NeXT, that would likely
require changes to all architecture specific code. Not advised!
What would be easy to do is to change confinit in main.c so that the
two banks are set up to point to the two largest contiguous blocks
of memory.
It sounds like in your case you have
bank 0: 4 Meg, bank 1: 4 Meg, bank 2: 16 Meg bank 3: 16 Meg
if you moved your memory around so that it was
bank 0: 16 Meg, bank 1: 4 Meg, bank 2: 16 Meg bank 3: 4 Meg
you could get all 40 Meg and still have two Plan 9 banks. (one
starting at 0x4000000 and the second starting at 0x6000000.)
But the easiest thing in your case is to use the 32 Meg in the
upper banks. Change the hard-wired address in confinit.
0x4000000 becomes 0x6000000 and 0x50000000 becomes 0x7000000
Each of these changes must be made twice in that routine.
The trickiest part of this fix, which would then only work on your
machine, is to also one bit in an undocumented constant in l.s.
Here is a fragment of my code:
/* Changed by PGW 9/17/95 from $0x0401A020 to $0x0403A020 */
/* in order to extend the NeXT Memory from 32 Meg to 64 Meg */
MOVL $0x0403A020, R0
its the 5th line in the start routine in l.s.
Another fix, not requiring any changes to the kernel is to move
your memory around so that you have
bank 0: 16 Meg, bank 1: 16 Meg, bank 2: 4 Meg bank 3: 4 Meg
This way you get 32 Meg for Plan 9 and 40 Meg for NeXTstep.
By the way, I have never had any problems rebuilding 9nextstation.
Regards,
Peter G. Weiner
next reply other threads:[~1995-10-05 15:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
1995-10-05 15:27 peter [this message]
-- strict thread matches above, loose matches on Subject: below --
1995-10-05 8:26 Ta-Wei
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