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From: Adrien Mazarguil <adrien.mazarguil@6wind.com>
To: "Richardson, Bruce" <bruce.richardson@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header
Date: Tue, 10 Nov 2015 17:08:06 +0100	[thread overview]
Message-ID: <20151110160806.GV4013@6wind.com> (raw)
In-Reply-To: <59AF69C657FD0841A61C55336867B5B03598018B@IRSMSX103.ger.corp.intel.com>

On Mon, Nov 09, 2015 at 02:02:28PM +0000, Richardson, Bruce wrote:
[...]
> > From: Adrien Mazarguil [mailto:adrien.mazarguil@6wind.com]
[...]
> > Untested but I guess modifying that function accordingly would look like:
> > 
> >  static inline void
> >  rte_pmd_debug_trace(const char *func_name, const char *fmt, ...)
> >  {
> >          va_list ap;
> >          va_start(ap, fmt);
> > 
> >          static __thread char buffer[vsnprintf(NULL, 0, fmt, ap)];
> > 
> >          va_end(ap);
> > 	 va_start(ap, fmt);
> >          vsnprintf(buffer, sizeof(buffer), fmt, ap);
> > 	 va_end(ap);
> >          rte_log(RTE_LOG_ERR, RTE_LOGTYPE_PMD, "%s: %s", func_name,
> > buffer);
> >  }
> > 
> 
> Looks a much better option.
> 
> From this, though, I assume then that we are only looking to support the -pedantic flag in conjuction with c99 mode or above. Supporting -pedantic with the pre-gcc-5 versions won't allow that to work though, as variably sized arrays only came in with c99, and were gnu extensions before that.

Right, -pedantic must follow a given standard such as -std=gnu99 otherwise
it's meaningless.

However pre-GCC 5 is fine for most if not all features we use, see:

 https://gcc.gnu.org/c99status.html

Mixed code and declarations are supported since GCC 3.0, __VA_ARGS__ in
macros since GCC 2.95 and variable length arrays since GCC 0.9, so as long
as we use a version that implements -std=gnu99 (or -std=c99 to be really
pedantic), it's fine.

Besides DPDK already uses C99 extensively, even a few C11 features (such as
embedded anonymous struct definitions) currently supported in C99 mode as
compiler extensions. I think we can safely ignore compilers that don't
support common C99 features.

-- 
Adrien Mazarguil
6WIND

  parent reply	other threads:[~2015-11-10 16:08 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-12 11:28 [dpdk-dev] [PATCH 0/4] ethdev: Add checks for function support in driver Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 1/4] ethdev: rename macros to have RTE_ETH prefix Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 2/4] ethdev: move RTE_ETH_FPTR_OR_ERR macros to header Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 3/4] ethdev: remove duplicated debug functions Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 4/4] ethdev: check support for rx_queue_count and descriptor_done fns Bruce Richardson
2015-06-12 17:32   ` Roger B. Melton
2015-06-15 10:14     ` Bruce Richardson
2015-07-06 15:11       ` Thomas Monjalon
2015-07-26 20:44         ` Thomas Monjalon
2015-09-09 15:09 ` [dpdk-dev] [PATCH v2 0/4] ethdev: minor cleanup Bruce Richardson
2015-09-09 15:09   ` [dpdk-dev] [PATCH v2 1/4] ethdev: rename macros to have RTE_ETH prefix Bruce Richardson
2015-09-09 15:09   ` [dpdk-dev] [PATCH v2 2/4] ethdev: move error checking macros to header Bruce Richardson
2015-09-09 15:09   ` [dpdk-dev] [PATCH v2 3/4] ethdev: remove duplicated debug functions Bruce Richardson
2015-09-09 15:09   ` [dpdk-dev] [PATCH v2 4/4] ethdev: check driver support for functions Bruce Richardson
2015-09-28 10:23   ` [dpdk-dev] [PATCH v2 0/4] ethdev: minor cleanup Bruce Richardson
2015-11-03  1:11     ` Thomas Monjalon
2015-11-03 10:06       ` Bruce Richardson
2015-11-03 12:00   ` [dpdk-dev] [PATCH v3 " Bruce Richardson
2015-11-03 12:00     ` [dpdk-dev] [PATCH v3 1/4] ethdev: rename macros to have RTE_ETH prefix Bruce Richardson
2015-11-03 12:00     ` [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header Bruce Richardson
2015-11-04  1:19       ` Thomas Monjalon
2015-11-04 10:24         ` Adrien Mazarguil
2015-11-04 14:10           ` Bruce Richardson
2015-11-04 15:25             ` Adrien Mazarguil
2015-11-04 18:39           ` Stephen Hemminger
2015-11-05 15:09             ` Adrien Mazarguil
2015-11-05 15:17               ` Bruce Richardson
2015-11-06 11:49               ` Bruce Richardson
2015-11-06 17:10               ` Bruce Richardson
2015-11-06 17:22                 ` Bruce Richardson
2015-11-09 13:39                   ` Adrien Mazarguil
2015-11-09 13:50                     ` Adrien Mazarguil
2015-11-09 14:02                     ` Richardson, Bruce
2015-11-10 10:31                       ` Declan Doherty
2015-11-10 16:08                       ` Adrien Mazarguil [this message]
2015-11-10 16:21                         ` Richardson, Bruce
2015-11-10 17:12                           ` Adrien Mazarguil
2015-11-11 10:51                             ` Bruce Richardson
2015-11-03 12:00     ` [dpdk-dev] [PATCH v3 3/4] ethdev: remove duplicated debug functions Bruce Richardson
2015-11-03 12:00     ` [dpdk-dev] [PATCH v3 4/4] ethdev: check driver support for functions Bruce Richardson
2015-11-03 22:00       ` Stephen Hemminger
2015-11-04 14:15         ` Bruce Richardson
2015-11-17 12:21     ` [dpdk-dev] [PATCH v4 0/2] ethdev: debug code cleanup Bruce Richardson
2015-11-17 12:21       ` [dpdk-dev] [PATCH v4 1/2] ethdev: remove duplicated debug functions Bruce Richardson
2015-11-17 12:21       ` [dpdk-dev] [PATCH v4 2/2] ethdev: add sanity checks to functions Bruce Richardson
2015-11-17 15:53         ` Stephen Hemminger
2015-11-24 14:56           ` Bruce Richardson
2015-11-24 15:29             ` Thomas Monjalon
2015-11-24 15:45               ` Bruce Richardson
2015-11-24 15:48                 ` Thomas Monjalon
2015-11-24 17:37       ` [dpdk-dev] [PATCH v5 0/2] ethdev: debug code cleanup Bruce Richardson
2015-11-24 17:37         ` [dpdk-dev] [PATCH v5 1/2] ethdev: remove duplicated debug functions Bruce Richardson
2015-11-25 18:14           ` Thomas Monjalon
2015-11-24 17:37         ` [dpdk-dev] [PATCH v5 2/2] ethdev: add sanity checks to functions Bruce Richardson
2015-11-25 18:21         ` [dpdk-dev] [PATCH v5 0/2] ethdev: debug code cleanup Thomas Monjalon
2015-11-06 11:52 [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header Bruce Richardson
2015-11-06 12:25 ` Adrien Mazarguil
2015-11-06 14:39   ` Richardson, Bruce
2015-11-06 14:54     ` Adrien Mazarguil
2015-11-06 15:30       ` Richardson, Bruce

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