Re: [dpdk-dev] pmdinfogen issues: cross compilation for ARM fails with older host compiler

[Hemant Agrawal <hemant.agrawal@nxp.com>]

> On Mon, Nov 14, 2016 at 02:29:24AM +0530, Jerin Jacob wrote:
> > 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
> >
> >
> That would be accurate.  That is to say, pmdinfogen is a tool that should only be
> run on the host doing the build, by the host doing the build, and so should be
> compiled to run on the host, not on the target being built for.
> 
> Yeah, so what we need is a way to get to the host version of rte_byteorder.h
> when building in a cross environment
> 
+1 

> Neil