[HRTIMER]: Add highres=noverify option to bypass clocksource verification
This disregards the CLOCK_SOURCE_MUST_VERIFY flag on all clocksources.
This is particularly useful on legacy x86_32 systems that have no ACPI,
LAPIC, or HPET timers, where only TSC and PIT are available.
Thanks to Chris Snook for suggesting this.
---
include/linux/clocksource.h | 2 ++
kernel/hrtimer.c | 2 ++
kernel/time/clocksource.c | 3 ++-
3 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 55e434f..90ae835 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -104,6 +104,8 @@ extern struct clocksource *clock; /* current clocksource */
#define CLOCK_SOURCE_WATCHDOG 0x10
#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
+extern int clocksource_noverify;
+
/* simplify initialization of mask field */
#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index ab80515..2fdf59f 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -476,6 +476,8 @@ static int __init setup_hrtimer_hres(char *str)
hrtimer_hres_enabled = 0;
else if (!strcmp(str, "on"))
hrtimer_hres_enabled = 1;
+ else if (!strcmp(str, "noverify"))
+ clocksource_noverify = 1;
else
return 0;
return 1;
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index dadde53..d3c14c1 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -54,6 +54,7 @@ static LIST_HEAD(clocksource_list);
static DEFINE_SPINLOCK(clocksource_lock);
static char override_name[32];
static int finished_booting;
+int clocksource_noverify;
/* clocksource_done_booting - Called near the end of core bootup
*
@@ -165,7 +166,7 @@ static void clocksource_check_watchdog(struct clocksource *cs)
unsigned long flags;
spin_lock_irqsave(&watchdog_lock, flags);
- if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
+ if (!clocksource_noverify && cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
int started = !list_empty(&watchdog_list);
list_add(&cs->wd_list, &watchdog_list);
--
1.5.6.4
On Wed, 8 Oct 2008, Chris Snook wrote:
--
