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SubjectRe: [PATCH] Re: x86_32 tsc/pit and hrtimers
On Wed, 8 Oct 2008, Jeff Hansen wrote:

> [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(-)

Oops, missing update to Documentation/kernel-parameters.txt.
Please see Documentation/SubmitChecklist :)
Thanks.

> 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);
>

--
~Randy


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