Re: [Xen-devel] [PATCH v3A 2/3] tools/libxc: allow controlling the max C-state sub-state

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2014-06-23 at 16:43 +0100, Jan Beulich wrote:
> --- a/xen/include/public/sysctl.h
> +++ b/xen/include/public/sysctl.h
> @@ -354,7 +354,11 @@ struct xen_sysctl_pm_op {
>      /* set/reset scheduler power saving option */
>      #define XEN_SYSCTL_pm_op_set_sched_opt_smt    0x21
>  
> -    /* cpuidle max_cstate access command */
> +    /*
> +     * cpuidle max C-state and max C-sub-state access command:
> +     * Set cpuid to 0 for max C-state.
> +     * Set cpuid to 1 for max C-sub-state.

This seems pretty nasty. Since the sysctl interface is not fixed can't
we just turn the existing get/set_max_cstate fields into structs? Or
(less preferably) define C-sub-states to have bit 31 set.

Can we at least get some named constants instead of 0 and 1?

Ian.


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