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

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Nov 18, 2016 at 08:50:52AM -0500, Neil Horman wrote:
> On Fri, Nov 18, 2016 at 12:03:19PM +0000, Hemant Agrawal wrote:
> > > -----Original Message-----
> > > From: Neil Horman [mailto:nhorman@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. 
> > 
> Can someone test it on BSD?  I'd like to ensure we don't need to modify it for
> that platform
> 
> Neil
> 
> > > 
> > > 
> > > 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; \
> > >  })
> > > 

For compile on FreeBSD 10 we need "#include <sys/endian.h>" and this
works.

/Bruce