On Mon, 09 Feb 2026 22:14:04 +0000,
Colton Lewis [off-list ref] wrote:

We may want a partitioned PMU but not have FEAT_FGT to untrap the
specific registers that would normally be untrapped. Add a handler for
those registers in the fast path so we can still get a performance
boost from partitioning.

The idea is to handle traps for all the PMU registers quickly by
writing directly to the hardware when possible instead of hooking into
the emulated vPMU as the standard handlers in sys_regs.c do.

This seems extremely premature. My assumption is that PMU traps are
rare, and that doing a full exit should be acceptable. Until you
demonstrate the contrary, I don't want this sort of massive bloat in
the most performance-critical path.

"Start walking before you try to run".

	M.

-- 
Without deviation from the norm, progress is not possible.