On Tue, Aug 16, 2022 at 10:26:19AM +0800, Zhang Rui wrote: > On Mon, 2022-08-15 at 11:11 +0200, Peter Zijlstra wrote: > > On Sat, Aug 13, 2022 at 12:41:44AM +0800, Zhang Rui wrote: > > > smp_num_siblings can be larger than 2. > > > > Not on a P4 it can't ;-) > > Kernel code doesn't prevent this from happening, so it just depends on > how SMT ID is encoded in APICID. No P4 ever encountered had it different and since no P4 will ever be made again (I sincerely hope) we have a complete case. > Checking for smp_num_sibling > 1 is the right logic to detect HT > support, which is followed by all other kernel code except this one. :) I'm fine with making it consistent, I'm arguing with the subject calling this a fix, it is not, it's a functional no-op.
