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Subject[PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE
Date
From: Len Brown <len.brown@intel.com>

We don't want to export the pm_idle function pointer to modules.
Currently CONFIG_APM_CPU_IDLE w/ CONFIG_APM_MODULE forces us to.

CONFIG_APM_CPU_IDLE is of dubious value, it runs only on 32-bit
uniprocessor laptops that are over 10 years old. It calls into
the BIOS during idle, and is known to cause a number of machines
to fail.

Removing CONFIG_APM_CPU_IDLE and will allow us to stop exporting
pm_idle. Any systems that were calling into the APM BIOS
at run-time will simply use HLT instead.

cc: x86@kernel.org
cc: Jiri Kosina <jkosina@suse.cz>
cc: stable@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>
---
Documentation/feature-removal-schedule.txt | 10 ++++++++++
arch/x86/kernel/apm_32.c | 2 ++
2 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 54db467..bab1acb 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -14,6 +14,16 @@ Who: Len Brown <len.brown@intel.com>

---------------------------

+What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
+When: 2.6.40
+Why: This optional sub-feature of APM is of dubious reliability,
+ and ancient APM laptops are likely better served by calling HLT.
+ Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
+ the pm_idle function pointer to modules.
+Who: Len Brown <len.brown@intel.com>
+
+----------------------------
+
What: PRISM54
When: 2.6.34

diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 0e4f24c..072546c 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -359,6 +359,7 @@ struct apm_user {
* idle percentage above which bios idle calls are done
*/
#ifdef CONFIG_APM_CPU_IDLE
+#warning deprecated CONFIG_APM_CPU_IDLE will be deleted in 2.6.40
#define DEFAULT_IDLE_THRESHOLD 95
#else
#define DEFAULT_IDLE_THRESHOLD 100
@@ -902,6 +903,7 @@ static void apm_cpu_idle(void)
unsigned int jiffies_since_last_check = jiffies - last_jiffies;
unsigned int bucket;

+ WARN_ONCE(1, "deprecated apm_cpu_idle will be deleted in 2.6.40");
recalc:
if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
use_apm_idle = 0;
--
1.7.5.rc0


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