[dpdk-users] Cross compile for ARM64 fails due to librte_vhost and pmdinfogen issues

[Thomas Monjalon]

2016-09-13 07:45, Michael Wildt:
> Hi Thomas,
> 
> Appreciate the assistance. Please see inline.
> 
> 
> On Tue, Sep 13, 2016 at 5:03 AM, Thomas Monjalon <thomas.monjalon at 6wind.com>
> wrote:
> 
> > Hi,
> >
> > 2016-09-12 22:20, Michael Wildt:
> > > I'm attempting to cross compile DPDK on an x86 for an ARM64 target. This
> > > fails in the following areas, using latest dpdk as of 9/12. When
> > compiling
> > > natively there are no issues.
> >
> > Your analysis below seems good.
> > Interestingly, I do not see such error (don't know why).
> > Please could you share the commands you are using?
> >
> 
> Sure can.
> 
> make config T=arm64-armv8a-linuxapp-gcc CROSS=/projects/ccxsw/
> toolchains/gcc-linaro-aarch64-linux-gnu-4.9-2014.09_linux/bin/aarch64-linux-gnu-
> ARCH=arm64
> 
> make T=arm64-armv8a-linuxapp-gcc CROSS=/projects/ccxsw/
> toolchains/gcc-linaro-aarch64-linux-gnu-4.9-2014.09_linux/bin/aarch64-linux-gnu-
> ARCH=arm64 RTE_KERNELDIR=/projects/kernel
> 
> > > - librte_vhost, fails with:
> > >
> > > /projects/dpdk_latest/lib/librte_vhost/vhost_user/virtio-
> > net-user.c:250:23:
> > > error: array subscript is above array bounds [-Werror=array-bounds]
> > >    rvq = dev->virtqueue[i * VIRTIO_QNUM + VIRTIO_RXQ];
> > [...]
> > > - buildtools/pmdinfogen, fails with:
> > >
> > > == Build buildtools/pmdinfogen
> > >   HOSTCC pmdinfogen.o
> > > /projects/dpdk_test_wget/dpdk-16.07/build/include/rte_byteorder.h:
> > > Assembler messages:
> > > /projects/dpdk_test_wget/dpdk-16.07/build/include/rte_byteorder.h:53:
> > > Error: no such instruction: `rev16 %bx,%bx'
> > [...]
> > >   - The issue is due to the rte_byteorder.h file which gets
> > >   symlink'ed with the ARM version at the beginning of the build.
> > >   The pmdinfogen is always compiled for x86 thus the asm is failing.

It is definitely something to fix.
In the meantime, you should be able to compile DPDK by using a more recent
toolchain. This error is in:

/* fix missing __builtin_bswap16 for gcc older then 4.8 */
#if !(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))

I know you are using gcc-4.9 but maybe __GNUC_MINOR__ is wrong in yours.