Re: x86: A fast way to check capabilities of the current cpu

From: H. Peter Anvin
Date: Wed Dec 15 2010 - 16:04:54 EST


On 12/15/2010 12:56 PM, Andrew Morton wrote:
> On Wed, 15 Dec 2010 14:07:39 -0600 (CST)
> Christoph Lameter <cl@xxxxxxxxx> wrote:
>
>> +#define cpu_has(c, bit) \
>> + (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \
>> test_cpu_cap(c, bit))
>>
>> +#define this_cpu_has(bit) \
>> + (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \
>> + this_cpu_test_bit(bit, (unsigned long *)&cpu_info.x86_capability))
>> +
>
> Isn't
>
> a ? 1 : b
>
> a complex way of writing
>
> a || b
>

Not if b is not a bool.

-hpa

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