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[204.195.22.127]) by smtp.gmail.com with ESMTPSA id u16sm2853727pje.6.2019.06.07.11.35.18 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 07 Jun 2019 11:35:18 -0700 (PDT) Date: Fri, 7 Jun 2019 11:35:12 -0700 From: Stephen Hemminger To: "Ananyev, Konstantin" Cc: "dev@dpdk.org" , "Richardson, Bruce" , Andrew Rybchenko Message-ID: <20190607113512.3a24bff6@hermes.lan> In-Reply-To: <2601191342CEEE43887BDE71AB97725801688E1B70@IRSMSX104.ger.corp.intel.com> References: <20190516180427.17270-1-stephen@networkplumber.org> <20190605180948.22414-1-stephen@networkplumber.org> <20190605180948.22414-6-stephen@networkplumber.org> <2601191342CEEE43887BDE71AB97725801688E1B70@IRSMSX104.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [dpdk-dev] [PATCH v4 5/8] net/ether: mark ethernet addresses as being 2-byte aligned X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Fri, 7 Jun 2019 16:59:32 +0000 "Ananyev, Konstantin" wrote: > > -----Original Message----- > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen Hemminger > > Sent: Wednesday, June 5, 2019 7:10 PM > > To: dev@dpdk.org > > Cc: Richardson, Bruce ; Stephen Hemminger <= stephen@networkplumber.org>; Andrew Rybchenko > > > > Subject: [dpdk-dev] [PATCH v4 5/8] net/ether: mark ethernet addresses a= s being 2-byte aligned > >=20 > > From: Bruce Richardson > >=20 > > When including the rte_ether.h header in applications with warnings > > enabled, a warning was given because of the assumption of 2-byte alignm= ent > > of ethernet addresses when processing them. > >=20 > > .../include/rte_ether.h:149:2: warning: converting a packed =E2=80=98co= nst > > struct ether_addr=E2=80=99 pointer (alignment 1) to a =E2=80=98unalig= ned_uint16_t=E2=80=99 > > {aka =E2=80=98const short unsigned int=E2=80=99} pointer (alignment 2= ) may result in > > an unaligned pointer value [-Waddress-of-packed-member] > > 149 | const unaligned_uint16_t *ea_words =3D (const unaligned_uint16_t= *)ea; > > | ^~~~~ > >=20 > > Since ethernet addresses should always be aligned on a two-byte boundar= y, > > we can just inform the compiler of this assumption to remove the warnin= gs > > and allow us to always access the addresses using 16-bit operations. > >=20 > > Signed-off-by: Bruce Richardson > > Signed-off-by: Stephen Hemminger > > Reviewed-by: Andrew Rybchenko > > --- > > lib/librte_net/rte_ether.h | 11 ++++++----- > > 1 file changed, 6 insertions(+), 5 deletions(-) > >=20 > > diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h > > index feb35a33c94b..d7b76ddf63eb 100644 > > --- a/lib/librte_net/rte_ether.h > > +++ b/lib/librte_net/rte_ether.h > > @@ -58,7 +58,8 @@ extern "C" { > > * See http://standards.ieee.org/regauth/groupmac/tutorial.html > > */ > > struct rte_ether_addr { > > - uint8_t addr_bytes[RTE_ETHER_ADDR_LEN]; /**< Addr bytes in tx order */ > > + uint8_t addr_bytes[RTE_ETHER_ADDR_LEN] __rte_aligned(2); > > + /**< Addr bytes in tx order */ > > } __attribute__((__packed__)); =20 >=20 > Hmm, that would change layout of any struct/union that has struct rte_eth= er_addr inside. > So seems like implicit ABI breakage to me. > Konstantin There was no rte_ether_addr in previous releases.