powerpc/148003: FreeBSD 8.1 RC1 (and earlier) install CDs fail with kernel trap on 700Mhz iMAC.

[tom armistead]

>Number:         148003
>Category:       powerpc
>Synopsis:       FreeBSD 8.1 RC1 (and earlier) install CDs fail with kernel trap on 700Mhz iMAC.
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-ppc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Jun 20 03:00:13 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     tom armistead
>Release:        8.1 RC1 (powerpc)
>Organization:
>Environment:
Can't get that far...
>Description:

The FreeBSD install CD does not boot on a 700Mhz iMAC.   It fails with a kernel trap shortly after the kernel is started.

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 it was 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.     

  
>How-To-Repeat:
Power on the machine and get into open firmware.

enter 'boot cd:,\boot\loader cd:0'

The loader runs ok and loads and starts the kernel.   The kernel fails right away after it is started.

The same type of failure also occurs when using the 7.2 and 8.0 install CD.
>Fix:




>Release-Note:
>Audit-Trail:
>Unformatted: