Re: Not able to use HIGH_RES_TIMERS on ARM

[Ajeet Yadav]

On Mon, Mar 19, 2012 at 6:34 PM, Russell King - ARM Linux
<linux@xxxxxxxxxxxxxxxx> wrote:
> On Mon, Mar 19, 2012 at 06:31:44PM +0530, Ajeet Yadav wrote:
>> Hi John, refering to you patch:
>>
>> ARM: remove 'select GENERIC_TIME'
>> GENERIC_TIME is now enabled by default, so 'select GENERIC_TIME' is
>> redundant. ÂRemove them.
>>
>> The following config's are not selectable:
>> config NO_HZ, config HIGH_RES_TIMERS, config IRQSOFF_TRACER, config
>> PREEMPT_TRACER
>>
>> As far as I know, ARM now uses GENERIC_TIME via the arch_getoffset()
>> infrastructure, i.e ARCH_USES_GETTIMEOFFSET=y
>
> No. ÂIt is possible to select these options, but only if your platform
> uses the clockevent and clocksource infrastructure. ÂIf you're using that,
> then you must _not_ select ARCH_USES_GETTIMEOFFSET.
>
> ARCH_USES_GETTIMEOFFSET is for compatibility with old unconverted
> platforms, which are _not_ possible to use the above features.

Just before the patch "time: Kill off CONFIG_GENERIC_TIME" Generic
time was selectable option,
Therefore our target configuration with 2.6 kernel was
GENERIC_CLOCKEVENTS=y, ARCH_USES_GETTIMEOFFSET=y,
I conclude that GENERIC_CLOCKEVENTS is supported, hence I must set
ARCH_USES_GETTIMEOFFSET=n, in order to use NO_HZ, HIGH_RES_TIMERS,
IRQSOFF_TRACER, PREEMPT_TRACER
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