[OpenBIOS] [Qemu-ppc] FreeBSD powerpc issue
agraf at suse.de
Mon Aug 27 23:51:43 CEST 2012
On 27.08.2012, at 13:43, Segher Boessenkool <segher at kernel.crashing.org> wrote:
>>>> How do I flush the TLB?
>>> tlbie, and perhaps tlbsync.
>> The QEMU TLB only caches existing translations, never misses.
> I'm not sure what you mean here? No PowerPC hardware that I know of
> stores a "this address doesn't go anywhere" tag in the TLB, either
> (I don't think the architecture allows that even).
> I also don't see what it has to do with the problem. The scenario
> what we think is happening: the CPU has translations for the OF code
> space in its TLB, because it has run it before. The kernel removes
> the translations but doesn't do TLBIE on those. On real hardware,
> the TLB entries are still used. What does QEMU do?
Ah, I see. It depends. QEMU doesn't provide any guarantees that the TLB survives basically. We don't flush it often for book3s, but it can still happen. Maybe try to put a printf into the tlb flush handler function?
More information about the OpenBIOS