ahci power management

[Simon 'corecode' Schubert]

Johannes Hofmann wrote:
In which context are sysctl callbacks run? How would I avoid races
when modifying flags or accessing registers (to disable the PRCE intr
for example)? 
In the context of the calling thread, with the mp lock held.

Maybe setting flags with with atomic operations and do the real work
in the per port thread?
You could send a message to the port thread which in turn does all the work, without changing anything from within the sysctl.

cheers
 simon