• Len Brown's avatar
    ACPI: create "processor.bm_check_disable" boot param · d3e7e99f
    Len Brown authored
    processor.bm_check_disable=1" prevents Linux from checking BM_STS
    before entering C3-type cpu power states.
    
    This may be useful for a system running acpi_idle
    where the BIOS exports FADT C-states, _CST IO C-states,
    or _CST FFH C-states with the BM_STS bit set;
    while configuring the chipset to set BM_STS
    more frequently than perhaps is optimal.
    
    Note that such systems may have been developed
    using a tickful OS that would quickly clear BM_STS,
    rather than a tickless OS that may go for some time
    between checking and clearing BM_STS.
    
    Note also that an alternative for newer systems
    is to use the intel_idle driver, which always
    ignores BM_STS, relying Linux device drivers
    to register constraints explicitly via PM_QOS.
    
    https://bugzilla.kernel.org/show_bug.cgi?id=15886Signed-off-by: default avatarLen Brown <len.brown@intel.com>
    d3e7e99f
processor_idle.c 31.4 KB