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authorMichael Niewöhner <foss@mniewoehner.de>2021-09-25 00:10:30 +0200
committerNico Huber <nico.h@gmx.de>2021-10-16 09:11:23 +0000
commitc47fc4002261e241890c098335eaaf4cb51c844a (patch)
tree6351190fc6c33c63e596ac0e29b164bd44b82048
parent5c259642c2d59c551fb0e54a14d9eeeb878d1177 (diff)
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
-rw-r--r--src/soc/intel/common/block/pmc/Kconfig7
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 e3978e29dd..5e5e8d6184 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