Re: [PATCH 9/9] powerpc: A new cache shape aux vectors

["Tulio Magno Quites Machado Filho" <tuliom@linux.vnet.ibm.com>]

Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:


> diff --git a/arch/powerpc/include/uapi/asm/auxvec.h b/arch/powerpc/include/uapi/asm/auxvec.h
> index ce17d2c..79183d2 100644
> --- a/arch/powerpc/include/uapi/asm/auxvec.h
> +++ b/arch/powerpc/include/uapi/asm/auxvec.h
> @@ -16,6 +16,37 @@
>   */
>  #define AT_SYSINFO_EHDR		33
>
> -#define AT_VECTOR_SIZE_ARCH 6 /* entries in ARCH_DLINFO */
> +/*
> + * AT_*CACHEBSIZE above represent the cache *block* size which is
> + * the size that is affected by the cache management instructions.
> + *
> + * It doesn't nececssarily matches the cache *line* size which is
> + * more of a performance tuning hint. Additionally the latter can
> + * be different for the different cache levels.
> + *
> + * The set of entries below represent more extensive information
> + * about the caches, in the form of two entry per cache type,
> + * one entry containing the cache size in bytes, and the other
> + * containing the cache line size in bytes in the bottom 16 bits
> + * and the cache associativity in the next 16 bits.
> + *
> + * The associativity is such that if N is the 16-bit value, the
> + * cache is N way set associative. A value if 0xffff means fully
> + * associative, a value of 1 means directly mapped.
> + *
> + * For all these fields, a value of 0 means that the information
> + * is not known.
> + */
> +
> +#define AT_L1I_CACHESIZE	40
> +#define AT_L1I_CACHESHAPE	41
> +#define AT_L1D_CACHESIZE	42
> +#define AT_L1D_CACHESHAPE	43
> +#define AT_L2_CACHESIZE		44
> +#define AT_L2_CACHESHAPE	45
> +#define AT_L3_CACHESIZE		46
> +#define AT_L3_CACHESHAPE	47

These names will clash with the other ones defined by alpha and sh:

/* Shapes of the caches.  Bits 0-3 contains associativity; bits 4-7 contains
   log2 of line size; mask those to get cache size.  */
#define AT_L1I_CACHESHAPE	34
#define AT_L1D_CACHESHAPE	35
#define AT_L2_CACHESHAPE	36
#define AT_L3_CACHESHAPE	37

-- 
Tulio Magno