|PowerNow! and Cool'n'Quiet are AMD names for frequency
|management capabilities in AMD processors. As the hardware
|implementation changes in new generations of the processors,
|there is a different cpu-freq driver for each generation.
|Note that the driver's will not load on the "wrong" hardware,
|so it is safe to try each driver in turn when in doubt as to
|which is the correct driver.
|Note that the functionality to change frequency (and voltage)
|is not available in all processors. The drivers will refuse
|to load on processors without this capability. The capability
|is detected with the cpuid instruction.
|The drivers use BIOS supplied tables to obtain frequency and
|voltage information appropriate for a particular platform.
|Frequency transitions will be unavailable if the BIOS does
|not supply these tables.
|6th Generation: powernow-k6
|7th Generation: powernow-k7: Athlon, Duron, Geode.
|8th Generation: powernow-k8: Athlon, Athlon 64, Opteron, Sempron.
|Documentation on this functionality in 8th generation processors
|is available in the "BIOS and Kernel Developer's Guide", publication
|26094, in chapter 9, available for download from www.amd.com.
|BIOS supplied data, for powernow-k7 and for powernow-k8, may be
|from either the PSB table or from ACPI objects. The ACPI support
|is only available if the kernel config sets CONFIG_ACPI_PROCESSOR.
|The powernow-k8 driver will attempt to use ACPI if so configured,
|and fall back to PST if that fails.
|The powernow-k7 driver will try to use the PSB support first, and
|fall back to ACPI if the PSB support fails. A module parameter,
|acpi_force, is provided to force ACPI support to be used instead
|of PSB support.