Re: [Qemu-devel] [Qemu-ppc] [PATCH 01/10] ppc: Fix rfi/rfid/hrfi/... emulation

["Cédric Le Goater" <clg@kaod.org>]

On 06/20/2016 09:47 AM, Thomas Huth wrote:
> On 20.06.2016 08:17, Cédric Le Goater wrote:
>> On 06/20/2016 04:19 AM, David Gibson wrote:
>>> On Mon, Jun 20, 2016 at 07:12:38AM +1000, Benjamin Herrenschmidt wrote:
>>>> On Sun, 2016-06-19 at 19:23 +0200, Cédric Le Goater wrote:
>>>>>> You can run a 32-bit OS or firmware on ppc64, but it needs to know that
>>>>>> it's running on a 64-bit chip and do a few things differently.
>>>>>
>>>>> yes sure but qemu would still allow rfi under 64bit CPUs, that is what 
>>>>> I was concerned about. Is that ok ? 
>>>>
>>>> Why ? A real CPU won't allow it, why should we ?
>>>
>>> We shouldn't.  However, I'm inclined to in for now, until we have an
>>> OpenBIOS fix actually committed.  I'd prefer to keep the existing
>>> setup sorta-working when the current situation is unlikely to break
>>> working code, even though it's definitely wrong.
>>>
>>> BenH or Cédric, if you want to resend the hrfi fix patch with the
>>> 64-bit rfi support left in for no, that would be good.
>>
>> The current patch does not need fixing. I will send the OpenBIOS patch 
>> shortly after I have looked at the FPU exception.
>>
>> Linux ppc behaves the same on a 970. So we will need to fix the 'rfi's
>> there also. 
> 
> Really? Wow, that surprises me. That OpenBIOS code likely never ran on a
> real 970 hardware, so that's not too much surprising that the "rfi"
> sneaked in there, but the Linux kernel certainly ran on a real 970 once,
> so I wonder why it's not properly using rfid for the 970 yet?

I just learned that the support for 970 was removed from the 32bit kernel
long time ago. False alarm, my bad.

C.