On 23 April 2015 at 15:26, Greg Bellows <greg.bell...@linaro.org> wrote: > Good catch Edgar, we shouldn't trap if we are "going into a low-power > state".
You mean "if we are not going into a low-power state". > It sounds like we arrived at the following: > > wfi- check has_work before taking either the UDEF or HLT exception hereby > making it a noop. This is OK (as per the code sketch in my earlier message). > wfe - Never trap, making it always a noop. This includes undoing the > existing YIELD exception. No, the YIELD behaviour is correct for WFE. This is important to avoid us spinning for the rest of this vcpu's timeslice (never making progress because the other vcpu which could unblock us from this spinlock doesn't run). But we don't ever want to trap to EL2. -- PMM
