Re: [dpdk-dev] [PATCH 1/3 v3] librte_hash: Fix unsupported instruction `crc32' in i686 platform

["Qiu, Michael" <michael.qiu@intel.com>]

Hi, Yong

If the platform is i686, dpdk will use software crc function.

Thanks,
Michael

-----Original Message-----
From: Liu, Yong 
Sent: Wednesday, March 18, 2015 9:21 PM
To: Qiu, Michael; thomas.monjalon@6wind.com; dev@dpdk.org
Cc: yerden.zhumabekov@sts.kz
Subject: RE: [dpdk-dev] [PATCH 1/3 v3] librte_hash: Fix unsupported instruction `crc32' in i686 platform

Michael & Thomas,

Should we use software crc function replace of hardware crc function in 'crc32c_sse42_u64' when arch is i686?
Thus application still can use CRC32_SSE42_x64 algorithm for crc calculation when build with i686 configuration.
This may helpful for simplify application code.

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Michael Qiu
> Sent: Monday, March 09, 2015 1:58 PM
> To: dev@dpdk.org
> Cc: yerden.zhumabekov@sts.kz
> Subject: [dpdk-dev] [PATCH 1/3 v3] librte_hash: Fix unsupported 
> instruction `crc32' in i686 platform
> 
> CC rte_hash.o
> Error: unsupported instruction `crc32'
> 
> The root cause is that i686 platform does not support 'crc32q'
> Need make it only available in x86_64 platform
> 
> Signed-off-by: Michael Qiu <michael.qiu@intel.com>
> Acked-by: Yerden Zhumabekov <yerden.zhumabekov@sts.kz>
> ---
> v3 --> v2:
> 	Add sub function for #else which returns 0
> v2 --> v1:
>          Make crc32 instruction only works in X86 platform
> 
>  lib/librte_hash/rte_hash_crc.h | 46 
> +++++++++++++++++++++++++++++++++----
> -----
>  1 file changed, 36 insertions(+), 10 deletions(-)
> 
> diff --git a/lib/librte_hash/rte_hash_crc.h 
> b/lib/librte_hash/rte_hash_crc.h index d28bb2a..f1dbded 100644
> --- a/lib/librte_hash/rte_hash_crc.h
> +++ b/lib/librte_hash/rte_hash_crc.h
> @@ -47,6 +47,7 @@ extern "C" {
>  #include <stdint.h>
>  #include <rte_cpuflags.h>
>  #include <rte_branch_prediction.h>
> +#include <rte_common.h>
> 
>  /* Lookup tables for software implementation of CRC32C */  static 
> const uint32_t crc32c_tables[8][256] = {{ @@ -364,6 +365,7 @@ 
> crc32c_2words(uint64_t data, uint32_t init_val)
>  	return crc;
>  }
> 
> +#if defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_64)
>  static inline uint32_t
>  crc32c_sse42_u32(uint32_t data, uint32_t init_val)  { @@ -375,16 
> +377,6 @@ crc32c_sse42_u32(uint32_t data, uint32_t init_val)  }
> 
>  static inline uint32_t
> -crc32c_sse42_u64(uint64_t data, uint64_t init_val) -{
> -	__asm__ volatile(
> -			"crc32q %[data], %[init_val];"
> -			: [init_val] "+r" (init_val)
> -			: [data] "rm" (data));
> -	return init_val;
> -}
> -
> -static inline uint32_t
>  crc32c_sse42_u64_mimic(uint64_t data, uint64_t init_val)  {
>  	union {
> @@ -397,6 +389,40 @@ crc32c_sse42_u64_mimic(uint64_t data, uint64_t
> init_val)
>  	init_val = crc32c_sse42_u32(d.u32[1], init_val);
>  	return init_val;
>  }
> +#else
> +static inline uint32_t
> +crc32c_sse42_u32(__rte_unused uint32_t data,
> +		 __rte_unused uint32_t init_val)
> +{
> +	return 0;
> +}
> +
> +static inline uint32_t
> +crc32c_sse42_u64_mimic(__rte_unused uint32_t data,
> +		       __rte_unused uint32_t init_val) {
> +	return 0;
> +}
> +#endif
> +
> +#ifdef RTE_ARCH_X86_64
> +static inline uint32_t
> +crc32c_sse42_u64(uint64_t data, uint64_t init_val) {
> +	__asm__ volatile(
> +			"crc32q %[data], %[init_val];"
> +			: [init_val] "+r" (init_val)
> +			: [data] "rm" (data));
> +	return init_val;
> +}
> +#else
> +static inline uint32_t
> +crc32c_sse42_u64(__rte_unused uint64_t data,
> +		 __rte_unused uint64_t init_val)
> +{


	return crc32c_2words(data, init_val);


> +	return 0;
> +}
> +#endif
> 
>  #define CRC32_SW            (1U << 0)
>  #define CRC32_SSE42         (1U << 1)
> --
> 1.9.3