I am still not clear if this is just cache corruption through us notEspecially buggy steppings of C3s would stop snooping while in 'hlt', so it wouldn't surprise me if they stopped while doing a speed transition.
listening or whether we genuinely need to halt.
In the former caseSounds reasonable, unless that causes problems of its own. (My general experience with Via CPUs is that doing anything even slightly unusual will result in strange behaviour or outright buggyness.)
flushing and disabling the CPU caches ought to be sufficient.