Konstantin Belousov 2fe1339ea2 Some BIOSes ACPI bytecode needs to take (sleepable) acpi mutex for
acpi_GetInteger() execution.  Intel DMAR interrupt remapping code
needs to know UID of the HPET to properly route the FSB interrupts
from the HPET, even when interrupt remapping is disabled, and the code
is executed under some non-sleepable mutexes.

Cache HPET UIDs in the device softc at the attach time and provide
lock-less method to get UID, use the method from the dmar hpet
handling code instead of calling GetInteger().

Reported and tested by:	Larry Rosenman <ler@lerctr.org>
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-02-20 13:37:04 +00:00
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