On Tue, Jun 5, 2018 at 4:35 PM, Sudeep Holla [off-list ref] wrote:

Currently, ARM64 doesn't support updating the CPU topology masks on
CPU hotplug operations. ACPI PPTT support rely on that missing feature
which is technically not incorrect. Instead of reverting all the PPTT
support, let's keep it simple and disable ACPI PPTT support on ARM64
for time-being until the topology updates are added for CPU hotplug
operations.

When is that going to happen?

Nobody else uses PPTT now.