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From: r k <rkerur@gmail.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v3] test-pmd: Fix pointer aliasing error
Date: Thu, 11 Dec 2014 09:51:44 -0800
Message-ID: <CAFb4SLCjnFpx0KGv3_zVG49vbhEnpS_GLhM7SQtvUs-s2Wmh3A@mail.gmail.com> (raw)
In-Reply-To: <1930269.B5nWyJ5DBl@xps13>

Thomas, Michael,

Wouldn't it cause unaligned memory access (new changes as well as the
previous code)? Wondering if get_unaligned/put_unaligned macros similar to
the ones used in kernel be ported to user-space?

Thanks,
Ravi

On Wed, Dec 10, 2014 at 4:54 PM, Thomas Monjalon <thomas.monjalon@6wind.com>
wrote:
>
> > > app/test-pmd/csumonly.c: In function 'get_psd_sum':
> > > build/include/rte_ip.h:161: error: dereferencing pointer 'u16'
> > >         does break strict-aliasing rules
> > > build/include/rte_ip.h:157: note: initialized from here
> > >         ...
> > >
> > > The root cause is that, compile enable strict aliasing by default,
> > > while in function rte_raw_cksum() try to convert 'const char *'
> > > to 'const uint16_t *'.
> > >
> > > This patch is one workaround fix.
> > >
> > > Signed-off-by: Michael Qiu <michael.qiu@intel.com>
> > > ---
> > > v3 --> v2:
> > >     use uintptr_t instead of unsigned long to
> > >     save pointer.
> > >
> > > v2 --> v1:
> > >     Workaround solution instead of shut off the
> > >     gcc params.
> >
> > This workaround is to solve the compile issue of GCC strict-aliasing(Two
> > different type pointers should not be point to the same memory address).
> >
> > For GCC 4.4.7 it will definitely occurs if  flags "-fstrict-aliasing"
> > and "-Wall" used.
>
> Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>>
>
> Applied with a comment in the code.
>
> Thanks
> --
> Thomas
>

  reply	other threads:[~2014-12-11 17:51 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] " 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 [this message]
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
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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