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From: "Qiu, Michael" <michael.qiu@intel.com>
To: Michael Qiu <qdy220091330@gmail.com>, "dev@dpdk.org" <dev@dpdk.org>
Thread-Topic: [PATCH v3] test-pmd: Fix pointer aliasing error
Thread-Index: AQHQD8cg6//kKikCHUuP3ggaMBczHg==
Date: Fri, 5 Dec 2014 05:34:35 +0000
Message-ID: <533710CFB86FA344BFBF2D6802E60286C9CFE5@SHSMSX101.ccr.corp.intel.com>
References: <1417663711-19576-1-git-send-email-michael.qiu@intel.com>
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Subject: Re: [dpdk-dev] [PATCH v3] test-pmd: Fix pointer aliasing error
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Any comments about this version? a new workaround solution :)=0A=
=0A=
Thanks,=0A=
Michael=0A=
On 12/4/2014 9:35 PM, Michael Qiu wrote:=0A=
> app/test-pmd/csumonly.c: In function =91get_psd_sum=92:=0A=
> build/include/rte_ip.h:161: error: dereferencing pointer =91u16=92=0A=
> does break strict-aliasing rules=0A=
> build/include/rte_ip.h:157: note: initialized from here=0A=
> ...=0A=
>=0A=
> The root cause is that, compile enable strict aliasing by default,=0A=
> while in function rte_raw_cksum() try to convert 'const char *'=0A=
> to 'const uint16_t *'.=0A=
>=0A=
> This patch is one workaround fix.=0A=
>=0A=
> Signed-off-by: Michael Qiu <michael.qiu@intel.com>=0A=
> ---=0A=
> v3 --> v2:=0A=
> use uintptr_t instead of unsigned long to=0A=
> save pointer.=0A=
>=0A=
> v2 --> v1:=0A=
> Workaround solution instead of shut off the=0A=
> gcc params.=0A=
>=0A=
> lib/librte_net/rte_ip.h | 3 ++-=0A=
> 1 file changed, 2 insertions(+), 1 deletion(-)=0A=
>=0A=
> diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h=0A=
> index 61e4457..cda3436 100644=0A=
> --- a/lib/librte_net/rte_ip.h=0A=
> +++ b/lib/librte_net/rte_ip.h=0A=
> @@ -154,7 +154,8 @@ struct ipv4_hdr {=0A=
> static inline uint16_t=0A=
> rte_raw_cksum(const char *buf, size_t len)=0A=
> {=0A=
> - const uint16_t *u16 =3D (const uint16_t *)buf;=0A=
> + uintptr_t ptr =3D (uintptr_t)buf;=0A=
> + const uint16_t *u16 =3D (const uint16_t *)ptr;=0A=
> uint32_t sum =3D 0;=0A=
> =0A=
> while (len >=3D (sizeof(*u16) * 4)) {=0A=
=0A=