linux-kernel - Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation detection

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Date:   Tue, 13 Sep 2016 15:40:18 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <h.peter.anvin@...el.com>,
        Ingo Molnar <mingo@...e.hu>, Tony Luck <tony.luck@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tejun Heo <tj@...nel.org>, Borislav Petkov <bp@...e.de>,
        Stephane Eranian <eranian@...gle.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        David Carrillo-Cisneros <davidcc@...gle.com>,
        Shaohua Li <shli@...com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        Sai Prakhya <sai.praneeth.prakhya@...el.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation
 detection

On 09/08/2016 02:57 AM, Fenghua Yu wrote:
> --- a/arch/x86/include/asm/disabled-features.h
> +++ b/arch/x86/include/asm/disabled-features.h
> @@ -57,6 +57,7 @@
>  #define DISABLED_MASK15	0
>  #define DISABLED_MASK16	(DISABLE_PKU|DISABLE_OSPKE)
>  #define DISABLED_MASK17	0
> -#define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 18)
> +#define DISABLED_MASK18	0
> +#define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 19)

Are you sure you don't want to add RDT to disabled-features.h?  You have
a config option for it, so it seems like you should also be able to
optimize some of these checks away when the config option is off.