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

[Greg Kurz]

On Wed, 28 Jun 2017 12:23:06 +0200
Cédric Le Goater <address@hidden> wrote:

> 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. 
>  

According to https://patchwork.ozlabs.org/patch/776052/

POWER9 DD2's PVR is expected to be 0x004e1200

Cheers,

--
Greg

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