Re: [PATCH v2 10/19] ppc/pnv: Add a big-core mode that joins two regular cores

[Nicholas Piggin]

On Sat Jul 13, 2024 at 5:19 PM AEST, Cédric Le Goater wrote:
> On 7/12/24 14:02, Nicholas Piggin wrote:
> > POWER9 and POWER10 machines come in two variants, big-core and
> > small-core. Big-core machines are SMT8 from software's point of view,
> > but the low level platform topology ("xscom registers and pervasive
> > addressing"), these look more like a pair of small cores ganged
> > together.
> > 
> > Presently the way this is modelled is to create one SMT8 PnvCore and add
> > special cases to xscom and pervasive for big-core mode that tries to
> > split this into two small cores, but this is becoming too complicated to
> > manage.
> > 
> > A better approach is to create 2 core structures and ganging them
> > together to look like an SMT8 core in TCG. Then the xscom and pervasive
> > models mostly do not need to differentiate big and small core modes.
> > 
> > This change adds initial mode bits and QEMU topology handling to
> > split SMT8 cores into 2xSMT4 cores.
> > 
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>
>
> Looks good. See some proposal below,

[snip]

All make sense, thank you will do.

Thnaks,
Nick