From c25a3f8a7afc5350e35413064f73f2f5058f0d37 Mon Sep 17 00:00:00 2001 From: Nate Lawson Date: Wed, 19 Nov 2003 20:28:56 +0000 Subject: [PATCH] Improve the section on Cx states, documenting the removal of -1 as a valid value for cx_lowest. To disable sleeping, use machdep.cpu_idle_hlt instead. Update the version of the ACPI spec we implement. Approved by: re (implicitly) --- share/man/man4/acpi.4 | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/share/man/man4/acpi.4 b/share/man/man4/acpi.4 index 7dc7a73729b5..c5f3dda824f7 100644 --- a/share/man/man4/acpi.4 +++ b/share/man/man4/acpi.4 @@ -342,13 +342,20 @@ The counters are reset when is modified. .It Va hw.acpi.cpu.cx_lowest Zero-based index of the lowest CPU idle state to use. -A value of -1 disables ACPI CPU idle states. +A scheduling algorithm will select between 0...index for the state +to use during the next sleep. To enable ACPI CPU idling control, .Va machdep.cpu_idle_hlt must be set to 1. .It Va hw.acpi.cpu.cx_supported List of supported CPU idle states and their transition latency in microseconds. +Each state has a type, C1-3. +C1 is equivalent to the ia32 HLT instruction, C2 provides a deeper +sleep with the same semantics, and C3 provides the deepest sleep +but additionally requires bus mastering to be disabled. +Deeper sleeps provide more power savings but increased transition +latency when an interrupt occurs. .El .Sh COMPATIBILITY ACPI is only found and supported on i386/ia32, ia64, and amd64. @@ -364,7 +371,7 @@ ACPI is only found and supported on i386/ia32, ia64, and amd64. .%A "Microsoft Corporation" .%A "Phoenix Technologies Ltd." .%A "Toshiba Corporation" -.%D July 27 2000 +.%D August 25, 2003 .%T "Advanced Configuration and Power Interface Specification" .%O http://acpi.info/spec.htm .Re