IMAC G3 (700Mhz) 7.2 & 8.0 install fails with "fatal kernel trap:"

[tom armistead]

Thanks -- I've now tried 8.1 RC1 and found it failed in the same way. 

There are no messages from the kernel prior to the fatal kernel trap message.

I did some investigation...

The failure messages displayed with the 8.1 RC1 install attempt are:

fatal kernel trap:
     exception = 0x4 (instruction storage trap)
     virtual address = 0x59f3e8
     srr0 = 0x59f3e8
     srr1 = 0x8003030
     lr = 0x5c27bc
     curthread =0x83fb50
     pid = 0, com =
panic: instruction storage trap
Uptime: 1s

I disassembled the kernel and it looks like the failing address is in the subroutine moea_bootstrap().

  59f3d8:       60 00 00 00     nop
  59f3dc:       60 00 00 00     nop
  59f3e0:       7d 30 83 a6     mtibatu 0,r9
  59f3e4:       7c 11 83 a6     mtibatl 0,r0
  59f3e8:       4c 00 01 2c     isync          <<<< failure address
  59f3ec:       7d 38 83 a6     mtdbatu 0,r9
  59f3f0:       7c 19 83 a6     mtdbatl 0,r0


And I found a previous problem report that looks like the same issue:
   
http://lists.freebsd.org/pipermail/freebsd-ppc/2008-March/002661.html

There was a fix for that issue but it looks like it doesn't work for the CPU on the 700Mhz iMAC.

I think to really solve this problem, you have to shut off translation, load the BATs and then re-enable translation.    When I patched in a segment of code to do just that, the kernel booted and the installer started up.