From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yerden Zhumabekov <e_zhumabekov-8EHiFRVJVgQ@public.gmane.org>
Subject: Re: [PATCH 1/3 v2] librte_hash: Fix unsupported
 instruction `crc32' in i686 platform
Date: Tue, 10 Mar 2015 09:55:16 +0600
Message-ID: <54FE6B24.1080700@sts.kz>
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To: Thomas Monjalon <thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>, "Qiu, Michael"
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08.03.2015 0:39, Thomas Monjalon =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> 2015-03-06 01:39, Qiu, Michael:
>> On 3/6/2015 1:11 AM, Thomas Monjalon wrote:
>>> 2015-03-06 00:55, Michael Qiu:
>>>> ... skipped ...
>>>> =20
>>>> +#if defined RTE_ARCH_I686 || defined RTE_ARCH_X86_64
>>>>  static inline uint32_t
>>>>  crc32c_sse42_u32(uint32_t data, uint32_t init_val)
>>>>  {
>>>> @@ -373,7 +374,9 @@ crc32c_sse42_u32(uint32_t data, uint32_t init_va=
l)
>>>>  			: [data] "rm" (data));
>>>>  	return init_val;
>>>>  }
>>>> +#endif
>>> Wouldn't it be more elegant to define a stub which returns 0 in #else
>>> in order to remove #ifdef below?
>>> Not sure, matter of taste.
>> It may be not a good idea, see rte_hash_crc_8byte(), if no crc32
>> support, it will use crc32c_2words(), if we define a stub which return=
s
>> 0 in #else, then we need always check the return value whether it is
>> none-zero otherwise need fallback.
> I don't think so.
> The stub won't never been called because they are protected by the cpuf=
lag
> condition.

That would be a bad surprise if one tries to launch that pre-built
binary on SSE4.2-capable arch :) It's fine though, if binary portability
is out of scope here.

--=20
Sincerely,

Yerden Zhumabekov
State Technical Service
Astana, KZ