EST(4) | Device Drivers Manual (x86) | EST(4) |
est
— Enhanced
SpeedStep
est0 at cpu0
The est
driver provides support for
Enhanced SpeedStep introduced in Intel's first and second generation of
Pentium M processors. The following
sysctl(8) variables are
available with est
:
machdep.cpu.frequency.target
machdep.cpu.frequency.current
machdep.cpu.frequency.available
est
.Note, however, that these variables are not guaranteed to exist in the future versions of NetBSD.
acpicpu(4), x86/odcm(4), x86/powernow(4)
Intel Corporation, Intel Pentium M Processor., Datasheet, http://download.intel.com/support/processors/mobile/pm/sb/25261203.pdf, March, 2004.
Intel Corporation, Enhanced Intel SpeedStep Technology for the Intel Pentium M Processor., White Paper, http://download.intel.com/design/network/papers/30117401.pdf, March, 2004.
The est
driver is considered a legacy
interface to be used only with old systems. It is known to be problematic
with new CPUs. Furthermore, in the unlikely case where both
est
and
x86/ichlpcib(4) or
piixpcib(4) provide
support for SpeedStep, the PCI-based interfaces should not be accessed due
possible race conditions.
September 7, 2020 | NetBSD 10.99 |