Re: [PATCH v3] sched/topology: Enable topology_span_sane check only for debug builds

Peter Zijlstra
2025-02-05T10:16:12Z

On Wed, Feb 05, 2025 at 03:43:54PM +0530, K Prateek Nayak wrote:
> Hello Peter,
>
> Thank you for the background!
>
> On 2/5/2025 3:25 PM, Peter Zijlstra wrote:
> > On Wed, Feb 05, 2025 at 03:18:24PM +0530, K Prateek Nayak wrote:
> >
> > > Have there been any reports on an x86 system / VM where
> > > topology_span_sane() was tripped?
> >
> > At the very least Intel SNC 'feature' tripped it at some point. They
> > figured it made sense to have the LLC span two nodes.
> >
> > But I think there were some really dodgy VMs too.
> >
> > But yeah, its not been often. But basically dodgy BIOS/VM data can mess
> > up things badly enough for it to trip.
>
> Has it ever happened without tripping the topology_sane() check first
> on the x86 side?

That I can't remember, sorry :/