Re: [Qemu-devel] [PATCH 2/2] PPC: Cuda: Use cuda timer to expose tbfreq to guest

[Alexander Graf <agraf@suse.de>]

On 14.07.14 16:04, Mark Cave-Ayland wrote:
> On 13/07/14 21:36, Alexander Graf wrote:
>
>> Mac OS X calibrates a number of frequencies on bootup based on reading
>> tb values on bootup and comparing them to via cuda timer values.
>>
>> The only variable we can really steer well (thanks to KVM) is the cuda
>> frequency. So let's use that one to fake Mac OS X into believing the
>> bus frequency is tbfreq * 4. That way Mac OS X will automatically
>> calculate the correct timebase frequency.
>>
>> With this patch and the patch set I posted earlier I can successfully
>> run Mac OS X 10.2, 10.3 and 10.4 guests with -M mac99 on TCG and KVM.
>
> Fantastic! I thought you mentioned before that there was a problem 
> with the way in which OS X used the MMU which meant it wouldn't be 
> possible to run under KVM but I guess that has been fixed now?

Yes, a patch for that is on the KVM mailing list. I just relocate the 
instruction pointer "somewhere safe" when in split real mode. Very crude 
hack, but it works astonishingly well.

> Also do any of these changes help any of the *BSDs to boot further?

I don't know :). I've never tried to boot *BSD on PPC, so I have no idea 
where that's broken.


Alex