svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
attimer(4)
ATTIMER(4) BSD Kernel Interfaces Manual ATTIMER(4)
NAME
attimer — i8254 Programmable Interval Timer (AT Timer) driver
SYNOPSIS
This driver is a mandatory part of x86 kernels.
The following tunables are settable from the loader(8):
hint.attimer.X.clock
controls support for the event timer functionality. Setting this value
to 0 disables it. The default value is 1.
hint.attimer.X.timecounter
controls support for the time counter functionality. Setting this value
to 0 disables it. The default value is 1.
hw.i8254.freq
allows overriding the default counter frequency. The same value is also
available at run-time via the machdep.i8254_freq sysctl.
DESCRIPTION
This driver uses i8254 Programmable Interval Timer (AT Timer) hardware to
supply the kernel with one timecounter and one event timer, and to gener‐
ate sound tones for the system speaker. This hardware includes three
channels. Each channel includes a 16 bit counter which decreases with a
known, platform-dependent frequency. Counters can operate in several
different modes, including periodic and one-shot. The output of each
channel has platform-defined wiring: one channel is wired to the inter‐
rupt controller and may be used as event timer, one channel is wired to
the speaker and used to generate sound tones, and one timer is reserved
for platform purposes.
The attimer driver uses a single hardware channel to provide both time
counter and event timer functionality. To make this possible, the
respective counter must be running in periodic mode. As a result, the
one-shot event timer mode is supported only when time counter functional‐
ity is disabled.
The event timer provided by the driver is irrelevant to CPU power states.
SEE ALSO
apic(4), atrtc(4), eventtimers(4), hpet(4), timecounters(4)
BSD May 26, 2014 BSD