From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Subject: Re: pmdinfogen issues: cross compilation for ARM fails
 with older host compiler
Date: Mon, 14 Nov 2016 02:29:24 +0530
Message-ID: <20161113205924.GA11392@localhost.localdomain>
References: <DB5PR04MB1605F64CF0D986E0B2B26AF089BB0@DB5PR04MB1605.eurprd04.prod.outlook.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
Cc: Neil Horman <nhorman@tuxdriver.com>, "dev@dpdk.org" <dev@dpdk.org>,
 "users@dpdk.org" <users@dpdk.org>, "Jacob, Jerin" <Jerin.Jacob@cavium.com>,
 Jan Viktorin <viktorin@rehivetech.com>
To: Hemant Agrawal <hemant.agrawal@nxp.com>
Return-path: <dev-bounces@dpdk.org>
Content-Disposition: inline
In-Reply-To: <DB5PR04MB1605F64CF0D986E0B2B26AF089BB0@DB5PR04MB1605.eurprd04.prod.outlook.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Fri, Nov 11, 2016 at 10:34:39AM +0000, Hemant Agrawal wrote:
> Hi Neil,
>                Pmdinfogen compiles with host compiler. It usages rte_byteorder.h of the target platform.
> However, if the host compiler is older than 4.8, it will be an issue during cross compilation for some platforms.
> e.g. if we are compiling on x86 host for ARM, x86 host compiler will not understand the arm asm instructions.
> 
> /* fix missing __builtin_bswap16 for gcc older then 4.8 */
> #if !(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))
> static inline uint16_t rte_arch_bswap16(uint16_t _x)
> {
>                register uint16_t x = _x;
>                asm volatile ("rev16 %0,%1"
>                                     : "=r" (x)
>                                     : "r" (x)
>                                     );
>                return x;
> }
> #endif
> 
> One easy solution is that we add compiler platform check in this code section of rte_byteorder.h
> e.g
> #if !(defined __arm__ || defined __aarch64__)
> static inline uint16_t rte_arch_bswap16(uint16_t _x)
> {
>                return (_x >> 8) | ((_x << 8) & 0xff00);
> }
> #else ….
> 
> Is there a better way to fix it?

IMO, It is a HOST build infrastructure issue. If a host app is using the
dpdk service then it should compile and link against HOST target(in this
specific case, build/x86_64-native-linuxapp-gcc). I think, introducing the
HOSTTARGET kind of scheme is a clean solution.

/Jerin