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| author | Michael Niewöhner <foss@mniewoehner.de> | 2021-09-25 00:10:30 +0200 |
|---|---|---|
| committer | Nico Huber <nico.h@gmx.de> | 2021-10-16 09:11:23 +0000 |
| commit | c47fc4002261e241890c098335eaaf4cb51c844a (patch) | |
| tree | 6351190fc6c33c63e596ac0e29b164bd44b82048 /src/soc/intel | |
| parent | 5c259642c2d59c551fb0e54a14d9eeeb878d1177 (diff) | |
| download | coreboot-c47fc4002261e241890c098335eaaf4cb51c844a.tar.gz coreboot-c47fc4002261e241890c098335eaaf4cb51c844a.tar.bz2 coreboot-c47fc4002261e241890c098335eaaf4cb51c844a.zip | |
soc/intel/pmc: add a note about legacy OSes/payloads to PM Timer Kconfig
Since ACPI 5.0A it is allowed to disable the ACPI Timer, when the
according FADT flag `ACPI_FADT_PLATFORM_CLOCK` is unset.
Starting with Skylake, most platforms (except Xeon-SP) support PM Timer
emulation, so even legacy OSes and payloads should work fine with the
hardware PM Timer disabled. However, when the `TMR_STS` functionality
is required, some legacy OSes might still not work (properly).
Add a note about this to the Kconfig help.
Change-Id: I53f1814113902124779ed85da030374439570688
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58018
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Lance Zhao
Diffstat (limited to 'src/soc/intel')
| -rw-r--r-- | src/soc/intel/common/block/pmc/Kconfig | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/soc/intel/common/block/pmc/Kconfig b/src/soc/intel/common/block/pmc/Kconfig index e3978e29dd52..5e5e8d618419 100644 --- a/src/soc/intel/common/block/pmc/Kconfig +++ b/src/soc/intel/common/block/pmc/Kconfig @@ -76,4 +76,11 @@ config USE_PM_ACPI_TIMER Disabling this option also stops the hardware TCO timer and makes the TCO watchdog unavailable. + Note: On platforms without uCode PM Timer emulation, legacy OSes + or payloads with ACPI version < 5.0A might not work without + PM ACPI timer. + + (Legacy) software requiring `TMR_STS` (for timer overflow + interrupts) will not work with this option disabled. + endif # PM_ACPI_TIMER_OPTIONAL |