Re: [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type

[Miles Glenn <milesg@linux.vnet.ibm.com>]

On Tue, 2023-11-21 at 19:26 +0100, Cédric Le Goater wrote:
> On 11/21/23 17:36, Miles Glenn wrote:
> > On Tue, 2023-11-21 at 08:29 +0100, Cédric Le Goater wrote:
> > > On 11/21/23 02:33, Nicholas Piggin wrote:
> > > > On Tue Nov 21, 2023 at 9:51 AM AEST, Glenn Miles wrote:
> > > > > Create a new powernv machine type, powernv10-rainier, that
> > > > > will contain rainier-specific devices.
> > > > 
> > > > Is the plan to have a base powernv10 common to all and then
> > > > powernv10-rainier looks like a Rainier? Or would powernv10
> > > > just be a rainier?
> > > > 
> > > > It's fine to structure code this way, I'm just wondering about
> > > > the machine types available to user. Is a base powernv10
> > > > machine
> > > > useful to run?
> > > 
> > > There are multiple P10 boards defined in Linux :
> > > 
> > >     aspeed-bmc-ibm-bonnell.dts
> > >     aspeed-bmc-ibm-everest.dts
> > >     aspeed-bmc-ibm-rainier-1s4u.dts
> > >     aspeed-bmc-ibm-rainier-4u.dts
> > >     aspeed-bmc-ibm-rainier.dts
> > > 
> > > and we could model the machines above with a fixed number of
> > > sockets.
> > > The "powernv10" would be the generic system that can be
> > > customized
> > > at will on the command line, even I2C devices. There is also the
> > > P10 Denali which is FSP based. This QEMU machine would certainly
> > > be
> > > very different. I thought of doing the same for P9 with a -zaius
> > > and include NPU2 models for it. I lacked time and the interest
> > > was
> > > small at the time of OpenPOWER.
> > > 
> > > Anyhow, adding a new machine makes sense and it prepares ground
> > > for
> > > possible new ones. I am OK with or without. As primary users, you
> > > are
> > > the ones that can tell if there will be a second machine.
> > >    
> > > Thanks,
> > > 
> > > C.
> > > 
> > 
> > I am not sure what the powernv10 machine would be used for.  The
> > only reason I kept it was because I didn't want to break anyone out
> > there that might be using it.
> (previous email sent to fast)
> 
> You would need to go through the deprecation process [1] if you want
> to remove the machine. I suggest keeping it for now since it is two
> lines of type definition.
> 

Yes, I agree.

> > My preference would have been to just make powernv10-rainier an
> > alias of the powernv10 machine, but only one alias name per machine
> > is supported and there is already a plan to make "powernv" an
> > alias for the powernv10 machine.
> 
> yes. It might be time now for PowerNV and pSeries to update the
> default processor. Let's address that in the QEMU 9.0 cycle.
> 
> Thanks,
> 
> C.
> 
> [1] https://qemu.readthedocs.io/en/v8.1.0/about/deprecated.html
> 

Sounds good, thanks!

Glenn