at all (ie reads yield constant values). Display the width as the
difference between max and min so that constant timers have width
zero.
o Get the address of the timer from the XPmTmrBlk field instead of
the V1_PmTmrBlk field. The former is a generic address and can
specify a memory mapped I/O address. Remove <machine/bus_pio.h>
to account for this. The timer is now properly configured on
machines with ACPI v2 tables, whether PIO or MEMIO. Note that
the acpica code converts v1 tables into v2 tables so the address
is always present in XPmTmrBlk.
o Replace the TIMER_READ macro with a call to the read_counter()
function and add a barrier to make sure that we observe proper
ordering of the reads.