Re: [PATCH 1/1] x86: Hyper-V: Mark the Hyper-V clocksource as being high resolution

[Thomas Gleixner <tglx@linutronix.de>]

On Fri, 3 Jul 2015, K. Y. Srinivasan wrote:
> From: Vivek yadav <vyadav@microsoft.com>
> 
> By design, alternative clock sources listed are based on the resolution of
> current clock source. Once you set a  high resolution clock,
> only high resolution sources are returned.
> Mark Hyper-V clock source as a high resolution clock source.
> 
> Signed-off-by: Vivek yadav <vyadav@microsoft.com>
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> ---
>  arch/x86/kernel/cpu/mshyperv.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 9b5d7b5..0e507a0 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -151,7 +151,8 @@ static struct clocksource hyperv_cs = {
>  	.rating		= 400, /* use this when running on Hyperv*/
>  	.read		= read_hv_clock,
>  	.mask		= CLOCKSOURCE_MASK(64),
> -	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
> +	.flags		= CLOCK_SOURCE_IS_CONTINUOUS |
> +			  CLOCK_SOURCE_VALID_FOR_HRES,

No, this is wrong. The CLOCK_SOURCE_VALID_FOR_HRES flag is managed by
the core code and set when a clocksource fulfils the criteria.

The changelog above is not explaining what problem you are trying to
solve.

Thanks,

	tglx