linux_dsm_epyc7002/arch/x86/kernel/acpi
Len Brown 718be4aaf3 ACPI: skip checking BM_STS if the BIOS doesn't ask for it
It turns out that there is a bit in the _CST for Intel FFH C3
that tells the OS if we should be checking BM_STS or not.

Linux has been unconditionally checking BM_STS.
If the chip-set is configured to enable BM_STS,
it can retard or completely prevent entry into
deep C-states -- as illustrated by turbostat:

http://userweb.kernel.org/~lenb/acpi/utils/pmtools/turbostat/

ref: Intel Processor Vendor-Specific ACPI Interface Specification
table 4 "_CST FFH GAS Field Encoding"
Bit 1: Set to 1 if OSPM should use Bus Master avoidance for this C-state

https://bugzilla.kernel.org/show_bug.cgi?id=15886

Signed-off-by: Len Brown <len.brown@intel.com>
2010-07-22 16:54:27 -04:00
..
realmode x86: Document linker script ASSERT() quirk 2009-10-16 07:18:46 +02:00
boot.c x86, irq: Rename gsi_end gsi_top, and fix off by one errors 2010-06-09 13:34:06 -07:00
cstate.c ACPI: skip checking BM_STS if the BIOS doesn't ask for it 2010-07-22 16:54:27 -04:00
Makefile ACPI: processor: unify arch_acpi_processor_cleanup_pdc 2009-12-22 03:24:14 -05:00
sleep.c ACPI: Unconditionally set SCI_EN on resume 2010-05-12 01:12:18 -04:00
sleep.h x86: move suspend wakeup code to C 2008-04-17 17:41:37 +02:00
wakeup_32.S Rename .text.page_aligned to .text..page_aligned. 2010-03-03 11:26:00 +01:00
wakeup_64.S Merge branches 'x86/acpi', 'x86/apic', 'x86/asm', 'x86/cleanups', 'x86/mm', 'x86/signal' and 'x86/urgent'; commit 'v2.6.29-rc6' into x86/core 2009-02-24 21:50:43 +01:00
wakeup_rm.S x86: move suspend wakeup code to C 2008-04-17 17:41:37 +02:00