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

[Hemant Agrawal]

> -----Original Message-----
> From: Neil Horman [mailto:nhorman at tuxdriver.com]
> On Tue, Nov 15, 2016 at 09:34:16AM +0000, Hemant Agrawal wrote:
> > > 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
> >
> 
> Give this a try, I've tested it on linux, but not BSD.  From what I read the
> functions are not posix compliant, though they should exist on all BSD and Linux
> systems in recent history.  There may be some fiddling needed for Net and
> OpenBSD variants, but I think this is the right general direction.

+ 1
This patch works good for Linux. 

> 
> 
> diff --git a/buildtools/pmdinfogen/pmdinfogen.h
> b/buildtools/pmdinfogen/pmdinfogen.h
> index 1da2966..c5ef89d 100644
> --- a/buildtools/pmdinfogen/pmdinfogen.h
> +++ b/buildtools/pmdinfogen/pmdinfogen.h
> @@ -21,7 +21,6 @@
>  #include <elf.h>
>  #include <rte_config.h>
>  #include <rte_pci.h>
> -#include <rte_byteorder.h>
> 
>  /* On BSD-alike OSes elf.h defines these according to host's word size */
>  #undef ELF_ST_BIND
> @@ -75,9 +74,9 @@
>  #define CONVERT_NATIVE(fend, width, x) ({ \
>  typeof(x) ___x; \
>  if ((fend) == ELFDATA2LSB) \
> -	___x = rte_le_to_cpu_##width(x); \
> +	___x = le##width##toh(x); \
>  else \
> -	___x = rte_be_to_cpu_##width(x); \
> +	___x = be##width##toh(x); \
>  	___x; \
>  })
>