On 1/24/25 12:17, Maciej Wieczor-Retman wrote: >> Could you poke around and see if there is any existing ABI that we can >> use to query LA57 support? Maybe one of the things KVM exports, or some >> TASK_SIZE_MAX comparisons? > Sure, I'll try to find some other way. > > My previous tactic was to munmap() a high address and see if it works. Does that > sound okay in case there isn't anything else would indicate la57 to userspace > reliably? Yeah, I think that's fine. I can't think of any obvious horrible pitfalls. All I'd ask is that you spend 20 minutes grepping for things that are conditional on X86_FEATURE_LA57 and see if there's anything else that's a good candidate.