NuBus PowerMacs and PDM video

NuBus PowerMacs and PDM video

[BenH]

Hi !

I'm doing some experiments with the MMU (learning it's usage). The goal
is to add some better bootstrap code to BootX (get rid of the -622 error
with MacOS VM) and to add support for the rather "special" memory
mappings of the NuBus PowerMacs.

However, I have a problem with the video on those machines: If I
understand things correctly, the framebuffer is set by MacOS to physical
address 0. This is a problem for us since we need to have some exception
vectors and other things like that in this location.

I beleive MkLinux booter moves it elswhere, but I don't know how to do
that (I don't have infos about the chip and I don't have one of those
machines to test with).

Any clues ?

-- 
           E-Mail: <mailto:bh40@calva.net>
BenH.      Web   : <http://calvaweb.calvacom.fr/bh40/>





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Re: NuBus PowerMacs and PDM video

[Michael R. Zucca]

At 7:14 AM -0500 2/9/99, BenH wrote:

>I'm doing some experiments with the MMU (learning it's usage). The goal
>is to add some better bootstrap code to BootX (get rid of the -622 error
>with MacOS VM) and to add support for the rather "special" memory
>mappings of the NuBus PowerMacs.

The PDM PowerMacs have their guts designed after 68k macs. They have the
same weird problems like aliasing, and a discontiguous memory.

>I beleive MkLinux booter moves it elswhere, but I don't know how to do
>that (I don't have infos about the chip and I don't have one of those
>machines to test with).

You just need to know the physical base address of the frame buffer.
Once you know that you can just rewrite the page tables to put the
frame buffer anywhere you'd like it.

You need to write a program under MacOS that will find a physical address
for a given virtual address. You'll probably need to do this in assembly
or there may even be a toolbox call that will do this for you.



_______________________________________________________________________
 Michael Zucca - mrz5149@acm.org - http://www.mdc.net/~mrz5149/
 "I will choose a path that's clear. I will choose Freewill. "
  --Rush, Freewill
_______________________________________________________________________



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Re: NuBus PowerMacs and PDM video

[BenH]

On Tue, Feb 9, 1999, Michael R. Zucca <mrz5149@acm.org> wrote:

>You just need to know the physical base address of the frame buffer.
>Once you know that you can just rewrite the page tables to put the
>frame buffer anywhere you'd like it.

I was thinking about the machines that store the framebuffer in main
memory (I beleive the 6100 does this). In this case, several people told
me that the physical address was actually 0. Anyway, I now have some code
to mess with the video controller, so I will be able to work around this
problem.

>You need to write a program under MacOS that will find a physical address
>for a given virtual address. You'll probably need to do this in assembly
>or there may even be a toolbox call that will do this for you.

There is a MacOS call for logical->physical mappings. The base address
sent by BootX to the kernel is already a physical address (actually both
are sent with BootX >= 1.0.2b1)


-- 
           E-Mail: <mailto:bh40@calva.net>
BenH.      Web   : <http://calvaweb.calvacom.fr/bh40/>





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Re: NuBus PowerMacs and PDM video

[Andre Tomt]

<cut>

I have a Apple Power Macintosh 6100/60 [0] that's in tip-top shape. I'll be 
happy to act as a beta tester for the NUBUS-port of LinuxPPC. I'm doing 
frequent backups so if the drive corrupts, I won't loose anything important,
 I hope ;)

it has 256Kb L2 cache and a 4.5GB IBM UWSCSI-3 HD (on the built-in bus). 
currently running Mac OS 8.5.1 and MkLinux DR3 gen#06.

so if there's any interest, I'll donate some of my spare time for this.


[0] the casing says 6100/60, but diagnostics-sw says it's a 66.

-- 
André Tomt      -   http://www.tomt.net
andre@tomt.net    -   tomt.net administrator

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Re: NuBus PowerMacs and PDM video

[Tom Vier]

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On Thu, 11 Feb 1999, Andre Tomt wrote:

> I have a Apple Power Macintosh 6100/60 [0] that's in tip-top shape. I'll be 
> happy to act as a beta tester for the NUBUS-port of LinuxPPC. I'm doing 
> frequent backups so if the drive corrupts, I won't loose anything important,
>  I hope ;)

i can also help. i have a 7100/80.

> it has 256Kb L2 cache and a 4.5GB IBM UWSCSI-3 HD (on the built-in bus). 
> currently running Mac OS 8.5.1 and MkLinux DR3 gen#06.

hehe. my 7100 has a 4gig uw seagate cuda. this box has such a nice hd,
but a 5mhz narrow scsi bus.

> [0] the casing says 6100/60, but diagnostics-sw says it's a 66.

what's the gestalt? that'll tell you. if it's 75 it's 60mhz, if it's
100 then it's 66mhz.

--
Tom Vier - 0x82B007A8
thomassr@erols.com       | goto the Zero Page at:
Tortured Souls Software  | http://www.erols.com/thomassr/zero/


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Re: NuBus PowerMacs and PDM video

[Andre Tomt]

Tom Vier said at ÒRe: NuBus PowerMacs and PDM videoÓ.
[1999/02/11 14:49]

>what's the gestalt? that'll tell you. if it's 75 it's 60mhz, if it's
>100 then it's 66mhz.

it's 100, ie 66MHz.

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Re: NuBus PowerMacs and PDM video

[Michael R. Zucca]

At 6:49 AM -0500 2/10/99, BenH wrote:

>Anyway, I now have some code
>to mess with the video controller, so I will be able to work around this
>problem.

What does the code reveal about the controller? Is it the MkLinux code?

>There is a MacOS call for logical->physical mappings. The base address
>sent by BootX to the kernel is already a physical address (actually both
>are sent with BootX >= 1.0.2b1)

I could see why you're confused, then. The booter sends you an address of
zero and it looks like a bug. :) However, the fact that the frame
buffer starts at 0 physical is weird but shouldn't be an impediment.

The last time I heard of Apple doing this was on the IIsi/IIci. We've been
avoiding the subject in NetBSD-mac68k for some time now :)


_______________________________________________________________________
 Michael Zucca - mrz5149@acm.org - http://www.mdc.net/~mrz5149/
 "I will choose a path that's clear. I will choose Freewill. "
  --Rush, Freewill
_______________________________________________________________________



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