Re: [Qemu-devel] [Qemu-ppc] [PATCH] target/ppc/cpu-models: set POWER9_v1.0 as POWER9 DD1

[Cédric Le Goater]

On 06/28/2017 11:18 AM, Laurent Vivier wrote:
> On 28/06/2017 11:11, Cédric Le Goater wrote:
>> On 06/28/2017 10:18 AM, David Gibson wrote:
>>> On Wed, Jun 28, 2017 at 09:09:24AM +0200, Thomas Huth wrote:
>>>> On 28.06.2017 03:42, address@hidden wrote:
>>>>> On Fri, Jun 23, 2017 at 04:10:55PM +0200, Laurent Vivier wrote:
>>>>>> On 23/06/2017 11:21, David Gibson wrote:
>>>>>>> On Thu, Jun 22, 2017 at 01:31:24PM +0200, Thomas Huth wrote:
>>>>>>>> On 22.06.2017 13:26, Laurent Vivier wrote:
>>>>>>>>> CPU_POWERPC_POWER9_DD1 is 0x004E0100, so this is the POWER9 v1.0.
>>>>>>>>>
>>>>>>>>> When we run qemu on a POWER9 DD1 host, we must use either
>>>>>>>>> "-cpu host" or "-cpu POWER9", but in the latter case it fails with
>>>>>>>>>
>>>>>>>>>     Unable to find sPAPR CPU Core definition
>>>>>>>>>
>>>>>>>>> because POWER9 DD1 doesn't appear in the list of known CPUs.
>>>>>>>>>
>>>>>>>>> This patch fixes this by defining POWER9_v1.0 with POWER9 DD1
>>>>>>>>> PVR instead of CPU_POWERPC_POWER9_BASE.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Laurent Vivier <address@hidden>
>>>>>>>>> ---
>>>>>>>>>  target/ppc/cpu-models.c | 2 +-
>>>>>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>>>>
>>>>>>>>> diff --git a/target/ppc/cpu-models.c b/target/ppc/cpu-models.c
>>>>>>>>> index 4d3e635..a22363c 100644
>>>>>>>>> --- a/target/ppc/cpu-models.c
>>>>>>>>> +++ b/target/ppc/cpu-models.c
>>>>>>>>> @@ -1144,7 +1144,7 @@
>>>>>>>>>      POWERPC_DEF("970_v2.2",      CPU_POWERPC_970_v22,                
>>>>>>>>> 970,
>>>>>>>>>                  "PowerPC 970 v2.2")
>>>>>>>>>  
>>>>>>>>> -    POWERPC_DEF("POWER9_v1.0",   CPU_POWERPC_POWER9_BASE,            
>>>>>>>>> POWER9,
>>>>>>>>> +    POWERPC_DEF("POWER9_v1.0",   CPU_POWERPC_POWER9_DD1,             
>>>>>>>>> POWER9,
>>>>>>>>>                  "POWER9 v1.0")
>>>>>>>>>  
>>>>>>>>>      POWERPC_DEF("970fx_v1.0",    CPU_POWERPC_970FX_v10,              
>>>>>>>>> 970,
>>>>>>>>>
>>>>>>>>
>>>>>>>> I think this also makes sense for running in TCG mode to get a valid
>>>>>>>> real PVR there.
>>>>>>>
>>>>>>> I'm not so convinced.
>>>>>>>
>>>>>>> IIUC, this will make TCG default (for now) to a DD1 POWER9.  That's a)
>>>>>>> probably not what anyone wants - who'd select a buggy prototype and b)
>>>>>>> not accurate - TCG does not implement DD1's bugs.
>>>>>>
>>>>>> According to the POWER8 user manual (I didn't fine the POWER9 one):
>>>>>>
>>>>>> "3.6.3.1 Processor Version Register (PVR)
>>>>>>
>>>>>> The processor revision level (PVR[16:31]) starts at x‘0100’, indicating
>>>>>> revision ‘1.0’. As revisions are made, bits [29:31] will indicate minor
>>>>>> revisions. Similarly, bits [20:23] indicate major changes."
>>>>>>
>>>>>> POWER9 DD1 PVR is 0x004E0100, so this is really version 1.0 of the 
>>>>>> POWER9.
>>>>>>
>>>>>> Perhaps we can define POWER9_v1.0 as CPU_POWERPC_POWER9_DD1, and
>>>>>> introduce a POWER9_v0.0 set to CPU_POWERPC_POWER9_BASE and define it as
>>>>>> the default one?
>>>>>
>>>>> I like the suggestion to set a v0.0 to CPU_POWERPC_POWER9_BASE. But, I
>>>>> think we could have only that option, removing the
>>>>> CPU_POWERPC_POWER9_DD1 entry.
>>>> I really dislike the idea of having a CPU called "v0.0" ... we do not
>>>> have this for any other CPU generation, and it sounds like it could be
>>>> very confusing for the users (you'd need to document somewhere what the
>>>> v0.0 exactly means). If we really want to go this way, I think we should
>>>> name it "POWER9-generic" or "PowerISA-3.0" or something similar instead.
>>>>
>>>> Or does somebody already know the exact PVR for DD2? If so, we could
>>>> simply add a POWER9_v2.0 CPU already and let the POWER9 alias point to
>>>> that version instead.
>>>
>>> Yes, I think that's a better idea.  I don't know the DD2 PVR, but I'm
>>> pretty sure we should be able to find out from someone at IBM.
>>>
>>> I've CCed Sam & Suraj - can you ask Mikey or someone what the PVR
>>> value for DD2.0 will be?
>>
>> I would expect something like :
>>
>>  0x200D104980000000UL; /* P9 Nimbus DD2.0 */
> 
> 
> I would expect something like 0x004Exxxx.

ah yes, I am mistaking the PVR and the CFAM ID. 

C.