From: "Mattias Rönnblom" <mattias.ronnblom@ericsson.com>
To: Jeff Shaw <jeffrey.b.shaw@intel.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] eal: remove variable length array
Date: Fri, 14 Dec 2018 21:28:05 +0100 [thread overview]
Message-ID: <3a573b56-6ea0-812c-4641-830fbd3c59cc@ericsson.com> (raw)
In-Reply-To: <20181214190713.GB9964@ae13-28.jf.intel.com>
On 2018-12-14 20:07, Jeff Shaw wrote:
>>> The code prior to this commit produced the following warning when
>>> compiled with "-Wvla -std=c90".
>>>
>>> warning: ISO C90 forbids variable length array ‘array’ [-Wvla]
>>>
>>> This commit removes the variable length array from the PMD debug
>>> trace function by allocating memory dynamically on the stack using
>>> alloca().
>>>
>>
>> Is alloca() even included in *any* C standard? As far as I see, it just
>> achieves the same thing in an uglier, less portable way than VLAs.
>
> I agree that it is much less elegant than a VLA. This is in preparation
> for DPDK on Windows, which using the Microsoft Visual C++ (MSVC) compiler.
> MSVC does not support variable length arrays. It does, however, support
> alloca(), as does GCC/ICC.
>
> For this particular instance, the point is moot, since the function is
> not used anywhere and can just as easily be removed. Though it does not
> address the issue for the ~100 other instances where VLAs are used. We
> will be submitting patches for those as more common files are ported to
> Windows.
>
If Microsoft's C compiler doesn't support C99, some 20 years after its
release, maybe it's time to find a new compiler, instead of messing up
the DPDK code in a ~100 instances.
next prev parent reply other threads:[~2018-12-14 20:28 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 16:38 Jeff Shaw
2018-12-14 18:36 ` Stephen Hemminger
2018-12-14 18:59 ` Jeff Shaw
2018-12-14 19:17 ` Jeff Shaw
2018-12-14 18:36 ` Mattias Rönnblom
2018-12-14 19:07 ` Jeff Shaw
2018-12-14 20:28 ` Mattias Rönnblom [this message]
2018-12-14 20:50 ` [dpdk-dev] [PATCH] eal: simplify RTE_PMD_DEBUG_TRACE Stephen Hemminger
2018-12-14 21:20 ` Jeff Shaw
2018-12-14 21:57 ` Stephen Hemminger
2018-12-21 16:17 ` Ferruh Yigit
2018-12-21 18:11 ` [dpdk-dev] [PATCH v2] " Jeff Shaw
2018-12-21 18:18 ` [dpdk-dev] [PATCH v3] " Jeff Shaw
2018-12-22 0:37 ` Ferruh Yigit
2018-12-19 21:45 ` [dpdk-dev] [PATCH] eal: remove variable length array Thomas Monjalon
2018-12-20 10:53 ` Mattias Rönnblom
2018-12-20 11:03 ` Thomas Monjalon
2018-12-14 20:40 ` [dpdk-dev] [PATCH v2] " Jeff Shaw
2018-12-15 14:26 ` Wiles, Keith
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