Re: [RFC][PATCH 1/3] x86: introduce disabled-features

From: H. Peter Anvin
Date: Fri Jun 20 2014 - 12:21:16 EST


On 06/20/2014 09:17 AM, Dave Hansen wrote:
> diff -puN /dev/null arch/x86/include/asm/disabled-features.h
> --- /dev/null 2014-04-10 11:28:14.066815724 -0700
> +++ b/arch/x86/include/asm/disabled-features.h 2014-06-20 09:15:38.968987152 -0700
> @@ -0,0 +1,33 @@
> +#ifndef _ASM_X86_DISABLED_FEATURES_H
> +#define _ASM_X86_DISABLED_FEATURES_H
> +
> +/* These features, although they might be available in a CPU
> + * will not be used because the compile options to support
> + * them are not present.
> + *
> + * This code allows them to be checked and disabled at
> + * compile time withut an explicit #ifdef. Simply call
> + * cpu_has() or this_cpu_has().
> + * */
> +
> +#ifdef CONFIG_X86_INTEL_MPX
> +# define HAVE_MPX (1<<(X86_FEATURE_MPX & 31))
> +#else
> +# define HAVE_MPX 0
> +#endif
> +

Is this an inverted test?

-hpa

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