[OpenBIOS] ppc64 MMU issues

[Blue Swirl]

On Mon, Nov 8, 2010 at 9:34 AM, Mark Cave-Ayland
<mark.cave-ayland at siriusit.co.uk> wrote:
> Andreas Färber wrote:
>
>> Since r945 everything except for the trampoline issue should be in SVN.
>
> Cool! :)
>
>> I've made no more progress throughout the week though:
>>
>> Directly after we set the MSR_IR|MSR_DR bits in the MSR
>> (arch/ppc/qemu/ofmem.c:setup_mmu), we get an ISI exception and end up in
>> arch/ppc/qemu/start.S:vector__0x400 (the 0xfffxxxxx one). We proceed up to
>> the bctrl which should take us to arch/ppc/qemu/ofmem.c:isi_exception, but
>> then get a 0x700 program exception. The value in ctr looks sensible, it's
>> some 0xfffxxxxx address.
>
> Hmmm this sounds similar to a SPARC32 issue I was finding over the weekend
> whereby everything died after the MMU was enabled because the context table
> wasn't correctly aligned. Could it be possible that the MMU hash tables
> aren't aligned correctly in memory?

Also the alignment may concern physical, not virtual addresses.