Re: [PATCH] arm64: Kconfig: Increase NR_CPUS default to 512

[Vanshidhar Konda]

On Mon, Jan 11, 2021 at 06:25:27PM +0000, Catalin Marinas wrote:
> On Mon, Jan 11, 2021 at 10:03:18AM -0800, Randy Dunlap wrote:
> > On 1/11/21 9:57 AM, Vanshidhar Konda wrote:
> > > On Mon, Jan 11, 2021 at 10:56:36AM +0000, Will Deacon wrote:
> > >> On Sat, Jan 09, 2021 at 09:36:15PM -0800, vanshikonda@xxxxxxxxxxxxxxxxxxxxxx wrote:
> > >>> From: Vanshidhar Konda <vanshikonda@xxxxxxxxxxxxxxxxxxxxxx>
> > >>>
> > >>> Increase the default value of NR_CPUS to 512 from 256. This will
> > >>> enable the defconfig kernel to support platforms that have upto
> > >>> 512 cores.
> > >>
> > >> Do we already support such a platform, and what is it? I'm fine with bumping.
> > >> the number, it's just nice to be able to say specifically _why_ we're dong
> > >> it.
> > >
> > > I'm not aware of any publicly available systems that run into the 256
> > > core limitation. At Ampere we have internal systems that would benefit
> > > from this change as they support more than 256 cores.
> >
> > But what does that have to do with the default value?
> > Do you expect to run defconfig kernels?
> > I don't ever expect that.
>
> We still aim for the arm64 defconfig to run on all supported SoCs, even
> if not optimally. Distros indeed tweak the config to their needs.

Would "all supported SoCs" mean only SoCs that are currently available
publicly? Could we include support for SoCs/systems in development but
to be available publicly in the next few years?

Thanks,
Vanshi

> --
> Catalin