Re: RED State Exception on E3500

[Julian Coleman <jdc%coris.org.uk@localhost>]

Hi,

> I expect this could be due to either bad hardware or somehow the 
> incorrect values are getting into the instruction cache.
> 
> If you want to determine for sure whether it's a hardware problem or a 
> software problem, you can add a little loop like the one in blast_icache 
> to clear out the instruction cache just before the RESTORE instruction.  
> Register scheduling may be an issue there, but traps are already disabled 
> so the code should be simpler.

Thanks for the explanation and patch.  Unfortunately, running with it made
no difference - another RED State Exception on CPU UPAID 6.  I ran `cpuctl
offline 0 6` (the 2 CPU's that I'd seen the exceptions on, but that crashed
with:

  trap type 0x10: cpu 4, pc=112ad60
  trap type 0x10: cpu 2, pc=112ad60 npc=112ad64 pstate=0x44820006<PRIV,IE>
  trap type 0x10: cpu 7, pc=112ad60 npc=112ad64 pstate=0x44820006<PRIV,IE>
  trap type 0x10: cpu 1, pc=112ad60kernel trap 10: illegal instruction

(0x112ad60 is the start of sysctl_kern_arnd() in src/sys/kern/init_sysctl.c.)

I'll try swapping out boards and see if I can get it stable.

Thanks again,

J

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