Re: [PATCH 06/13] ppc/spapr: Add pa-features for POWER10 machines

[BALATON Zoltan]

On Tue, 12 Mar 2024, Nicholas Piggin wrote:
> On Tue Mar 12, 2024 at 7:07 AM AEST, BALATON Zoltan wrote:
> > On Mon, 11 Mar 2024, Philippe Mathieu-Daudé wrote:
> > > On 11/3/24 19:51, Nicholas Piggin wrote:
> > > > From: Benjamin Gray <bgray@linux.ibm.com>
> > > >
> > > > Add POWER10 pa-features entry.
> > > >
> > > > Notably DEXCR and and [P]HASHST/[P]HASHCHK instruction support is
> > > > advertised. Each DEXCR aspect is allocated a bit in the device tree,
> > > > using the 68--71 byte range (inclusive). The functionality of the
> > > > [P]HASHST/[P]HASHCHK instructions is separately declared in byte 72,
> > > > bit 0 (BE).
> > > >
> > > > Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
> > > > [npiggin: reword title and changelog, adjust a few bits]
> > > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> > > > ---
> > > >   hw/ppc/spapr.c | 34 ++++++++++++++++++++++++++++++++++
> > > >   1 file changed, 34 insertions(+)
> > > >
> > > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > > > index 247f920f07..128bfe11a8 100644
> > > > --- a/hw/ppc/spapr.c
> > > > +++ b/hw/ppc/spapr.c
> > > > @@ -265,6 +265,36 @@ static void spapr_dt_pa_features(SpaprMachineState
> > > > *spapr,
> > > >           /* 60: NM atomic, 62: RNG */
> > > >           0x80, 0x00, 0x80, 0x00, 0x00, 0x00, /* 60 - 65 */
> > > >       };
> > > > +    /* 3.1 removes SAO, HTM support */
> > > > +    uint8_t pa_features_31[] = { 74, 0,
> > >
> > > Nitpicking because pre-existing, all these arrays could be static const.
> >
> > If we are at it then maybe also s/0x00/   0/ because having a stream of
> > 0x80 and 0x00 is not the most readable.
>
> Eh, it's more readable because it aligns colums.

Not sure it you've noticed the 3 spaces before the 0 replacing 0x0 that 
would keep alignment. But it's not something that needs to be changed just 
commented on it as it came up but I don't expect it to be done now on the 
day of the freeze. It's more important to get the already reviewed and 
queued patches in a pull request to not miss the release. So this comment 
is just for the fuuture.

Regards,
BALATON Zoltan

> But probably better
> more readable and  less error prone would be like -
>
>    PA_FEATURE_SET(pa_features_31,  6, 0); /* DS207 */
>    PA_FEATURE_SET(pa_features_31, 18, 0); /* Vector scalar */
>
> I just didn't quite find something I like yet. I won't change style
> before adding the missing bits either way, but certainly would be
> good to clean it up after.
>
> Thanks,
> Nick