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From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: "Qiu, Michael" <michael.qiu@intel.com>
Cc: dev@dpdk.org, Chao Zhu <chaozhu@linux.vnet.ibm.com>
Subject: Re: [dpdk-dev] [PATCH 1/2] eal: detect endianness
Date: Thu, 04 Dec 2014 10:00:09 +0100
Message-ID: <3580620.HEA1jLh5UM@xps13> (raw)
In-Reply-To: <533710CFB86FA344BFBF2D6802E60286C9C86D@SHSMSX101.ccr.corp.intel.com>

2014-12-04 02:28, Qiu, Michael:
> On 12/4/2014 5:26 AM, Thomas Monjalon wrote:
> > There is no standard to check endianness.
> > So we need to try different checks.
> > Previous trials were done in testpmd (see commits
> > 51f694dd40f56 and 64741f237cf29) without full success.
> > This one is not guaranteed to work everywhere so it could
> > evolve when exceptions are found.
[...]
> >  #include <stdint.h>
> > +#ifdef RTE_EXEC_ENV_BSDAPP
> > +#include <sys/endian.h>
> > +#else
> > +#include <endian.h>
> > +#endif
> > +
> > +/*
> > + * Compile-time endianness detection
> > + */
> > +#define RTE_BIG_ENDIAN    1
> > +#define RTE_LITTLE_ENDIAN 2
> > +#if defined __BYTE_ORDER
> > +#if __BYTE_ORDER == __BIG_ENDIAN
> > +#define RTE_BYTE_ORDER RTE_BIG_ENDIAN
> > +#elif __BYTE_ORDER == __LITTLE_ENDIAN
> > +#define RTE_BYTE_ORDER RTE_LITTLE_ENDIAN
> > +#endif /* __BYTE_ORDER */
> > +#elif defined __BYTE_ORDER__
> > +#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> > +#define RTE_BYTE_ORDER RTE_BIG_ENDIAN
> > +#elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> > +#define RTE_BYTE_ORDER RTE_LITTLE_ENDIAN
> > +#endif /* __BYTE_ORDER__ */
> > +#elif defined __BIG_ENDIAN__
> > +#define RTE_BYTE_ORDER RTE_BIG_ENDIAN
> > +#elif defined __LITTLE_ENDIAN__
> > +#define RTE_BYTE_ORDER RTE_LITTLE_ENDIAN
> > +#endif
> 
> What do you think about :
> 
> +/*
> +  * Compile-time endianness detection
> + */
> +#define RTE_BIG_ENDIAN 1
> +#define RTE_LITTLE_ENDIAN 2
> +if defined __BYTE_ORDER__    /* Prefer gcc build-in macros */
> +#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> +#define RTE_BYTE_ORDER RTE_BIG_ENDIAN
> +#elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> +#define RTE_BYTE_ORDER RTE_LITTLE_ENDIAN
> +#endif /* __BYTE_ORDER__ */
> +#else
> +#if defined RTE_EXEC_ENV_BSDAPP
> +#include <sys/endian.h>
> +#else
> +#include <endian.h>
> +#endif
> +#if defined __BYTE_ORDER
> +#if __BYTE_ORDER == __BIG_ENDIAN
> +#define RTE_BYTE_ORDER RTE_BIG_ENDIAN
> +#elif __BYTE_ORDER == __LITTLE_ENDIAN
> +#define RTE_BYTE_ORDER RTE_LITTLE_ENDIAN
> +#endif /* __BYTE_ORDER */
> +#elif defined __BIG_ENDIAN__
> +#define RTE_BYTE_ORDER RTE_BIG_ENDIAN
> +#elif defined __LITTLE_ENDIAN__
> +#define RTE_BYTE_ORDER RTE_LITTLE_ENDIAN
> +#endif
> +#endif

Please, could you give more explanations about your proposal?
Why not always try to include endian.h?
Why giving high priority to __BYTE_ORDER__?

-- 
Thomas

  reply	other threads:[~2014-12-04  9:00 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1417606044-3432-1-git-send-email-michael.qiu@intel.com>
     [not found] ` <1417606099-3489-1-git-send-email-michael.qiu@intel.com>
2014-12-03 11:42   ` [dpdk-dev] [PATCH] test-pmd: Fix pointer aliasing error Bruce Richardson
2014-12-03 13:59     ` Qiu, Michael
2014-12-03 14:51       ` Bruce Richardson
2014-12-03 15:19         ` Qiu, Michael
2014-12-03 15:36           ` Bruce Richardson
2014-12-04  2:38             ` Qiu, Michael
2014-12-04  3:28               ` [dpdk-dev] [PATCH v2] " Michael Qiu
2014-12-04  4:16                 ` [dpdk-dev] [PATCH v3] " Michael Qiu
2014-12-05  5:34                   ` Qiu, Michael
2014-12-05  9:24                     ` Thomas Monjalon
2014-12-08  1:28                       ` Qiu, Michael
2014-12-08  1:30                   ` Qiu, Michael
2014-12-10  3:44                     ` Qiu, Michael
2014-12-11  0:54                     ` Thomas Monjalon
2014-12-11 17:51                       ` r k
2014-12-12  6:49                         ` Qiu, Michael
2014-12-04 12:54                 ` [dpdk-dev] [PATCH v2] " Ananyev, Konstantin
2014-12-03 15:24     ` [dpdk-dev] [PATCH] " Olivier MATZ
2014-12-03 16:03       ` Dayu Qiu
2014-12-03 15:57     ` Dayu Qiu
2014-12-03 16:26 ` [dpdk-dev] [PATCH] test-pmd: Fix "__BYTE_ORDER__" not defined error Qiu, Michael
2014-12-03 19:59   ` Thomas Monjalon
2014-12-03 20:47     ` [dpdk-dev] [PATCH 0/2] fix endianness in EAL Thomas Monjalon
2014-12-03 20:47       ` [dpdk-dev] [PATCH 1/2] eal: detect endianness Thomas Monjalon
2014-12-04  2:28         ` Qiu, Michael
2014-12-04  9:00           ` Thomas Monjalon [this message]
2014-12-04 10:28             ` Qiu, Michael
2014-12-04 12:19               ` Thomas Monjalon
2014-12-04 12:50                 ` Qiu, Michael
2014-12-03 20:47       ` [dpdk-dev] [PATCH 2/2] app/testpmd: fix endianness detection Thomas Monjalon
2014-12-04  9:28       ` [dpdk-dev] [PATCH 0/2] fix endianness in EAL Chao Zhu
2014-12-05 16:01         ` Thomas Monjalon

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