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Re: S900 booting via quik

Hi Phil,

On  15 Mar, this message from Phil Brutsche echoed through cyberspace:
> A long time ago, in a galaxy far, far way, someone said...
>> > DEFAULT CATCH!, code=FFF00400
>> 0x0400 is 'ISI exception', problems fetching instructions. Basically
>>  means you cannot access your instructions (like in MMU setup problems,
>>  maybe caused by hosed PC register, jumps to nowhere...)
>> This one could be caused by a bad BAT (part of the MMU) setup within the
>> bootloader.
> Hrm...
>> > I wonder where I can find a copy of the processor manuals...
> Incidentally, Motorolla has quite a bit of documentation for PPC
> processors on their web site - it's just a matter of finding the right
> .pdf.
>> > Maybe they'll be able to tell me why I can't get a 2.4.x kernel to boot on
>> > my 601-based 7200 :) (I get a "DEFAULT CATCH!, code=FFF00700" until I cold
>> > boot it)
>> 0x0700 is 'Program Exception', means illegal instruction. Most probably
>> you're trying to execute bullsh...
> The NetBSD/powermac boot disk gives "code=FFF0700" when I try to boot the
> 7200 with it; the same disk works fine on the S900.

Now that rings a bell. In fact, quik had a bug that I discovered while
trying to boot my G3-upgraded box: in fact the BAT registers consist of
a high and a low part. In one of them, there is an 'enable' bit that
marks the BAT entry valid. Now, the location of that bit isn't the same
across all PPC processors. IIRC, the 601 has it in one half, the later
processors have it in the other part. Now you have to make sure that the
enable bit gets set _after_ the other half of the BAT was set; otherwise
you will enable the BAT mapping with only half of a sensible value in
there, which isn't that good ;-).

If you look at the source for the first-stage loader, you can fiund BAT
code in there. Have a look whether you see a distinction between
processor types in there.

> I wonder if PPC601 support was dropped in 2.4.x, or is somehow lagging
> behind 603 & higher processors...

Both should be supported; but there may have been (or be) bugs in quik
that are only triggered on some random implementation. IOW, some
processors may work, others may not.

>> What version of quik are you using? I'm running some old quik-1.3
>> version myself; I didn't want to go thorugh the trouble of getting
>> another version booting once I figured out for 1.3 ;-)
> I wonder if the 1.3 first stage loader doesn't like the 2.0 second stage
> loader.
>> If you are using some 2.x version, you might want to give 1.3 a try,
>> fith my first.b.
> Yes, I'm using 2.x - that's what gets installed by default by Debian
> 2.2r2.
> Do you have the source for 1.3 someplace?  I can't seem to find any
> reference as to where to get it - all I can find is some LinuxPPC binary
> RPMs that I can debianize with alien.




Michel Lanners                 |  " Read Philosophy.  Study Art.
23, Rue Paul Henkes            |    Ask Questions.  Make Mistakes.
L-1710 Luxembourg              |
email   mlan@cpu.lu            |
http://www.cpu.lu/~mlan        |                     Learn Always. "

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