svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
hpet(4)
HPET(4) BSD Kernel Interfaces Manual HPET(4)
NAME
hpet — High Precision Event Timer driver
SYNOPSIS
To compile this driver into the kernel, place the following lines in your
kernel configuration file:
device acpi
The following tunables are settable from the loader(8):
hint.hpet.X.allowed_irqs
is a 32bit mask. Each set bit allows driver to use respective IRQ, if
BIOS also set respective capability bit in comparator's configuration
register. Default value is 0xffff0000, except some known broken hard‐
ware.
hint.hpet.X.clock
controls event timers functionality support. Setting to 0, disables it.
Default value is 1.
hint.hpet.X.legacy_route
controls "LegacyReplacement Route" mode. If enabled, HPET will steal
IRQ0 of i8254 timer and IRQ8 of RTC. Before using it, make sure that
respective drivers are not using interrupts, by setting also:
hint.attimer.0.clock=0
hint.atrtc.0.clock=0
Default value is 0.
hint.hpet.X.per_cpu
controls how much per-CPU event timers should driver attempt to register.
This functionality requires every comparator in a group to have own
unshared IRQ, so it depends on hardware capabilities and interrupts con‐
figuration. Default value is 1.
DESCRIPTION
This driver uses High Precision Event Timer hardware (part of the
chipset, usually enumerated via ACPI) to supply kernel with one time
counter and several (usually from 3 to 8) event timers. This hardware
includes single main counter with known increment frequency (10MHz or
more), and several programmable comparators (optionally with automatic
reload feature). When value of the main counter matches current value of
any comparator, interrupt can be generated. Depending on hardware capa‐
bilities and configuration, interrupt can be delivered as regular I/O
APIC interrupt (ISA or PCI) in range from 0 to 31, or as Front Side Bus
interrupt, alike to PCI MSI interrupts, or in so called "LegacyReplace‐
ment Route" HPET can steal IRQ0 of i8254 and IRQ8 of the RTC. Interrupt
can be either edge- or level-triggered. In last case they could be
safely shared with PCI IRQs. Driver prefers to use FSB interrupts, if
supported, to avoid sharing. If it is not possible, it uses single
sharable IRQ from PCI range. Other modes (LegacyReplacement and ISA
IRQs) require special care to setup, but could be configured manually via
device hints.
Event timers provided by the driver support both one-shot an periodic
modes and irrelevant to CPU power states.
Depending on hardware capabilities and configuration, driver can expose
each comparator as separate event timer or group them into one or several
per-CPU event timers. In last case interrupt of every of those compara‐
tors within group is bound to specific CPU core. This is possible only
when each of these comparators has own unsharable IRQ.
SEE ALSO
acpi(4), apic(4), atrtc(4), attimer(4), eventtimers(4), timecounters(4)
HISTORY
The hpet driver first appeared in FreeBSD 6.3. Support for event timers
was added in FreeBSD 9.0.
BSD September 14, 2010 BSD