Re: [dpdk-dev] [PATCH] mk: disable warning with gcc 9 on Fedora 30

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

On Fri, May 03, 2019 at 04:01:38PM +0000, Jerin Jacob Kollanukkaran wrote:
> > -----Original Message-----
> > From: dev <dev-bounces@dpdk.org> On Behalf Of Thomas Monjalon
> > Sent: Thursday, May 2, 2019 9:27 PM
> > To: Reshma Pattan <reshma.pattan@intel.com>
> > Cc: dev@dpdk.org; David Marchand <david.marchand@redhat.com>
> > Subject: Re: [dpdk-dev] [PATCH] mk: disable warning with gcc 9 on Fedora 30
> > 
> > 02/05/2019 17:00, David Marchand:
> > > On Thu, May 2, 2019 at 11:33 AM Reshma Pattan
> > > <reshma.pattan@intel.com>
> > > wrote:
> > >
> > > > gcc 9 on Fedora 30 gives an error
> > > > "taking address of packed member may result in an unaligned pointer
> > > > value" warnings.
> > > >
> > > > For clang builds this warning is already disabled, so disable
> > > > "-Waddress-of-packed-member" for gcc builds also.
> > > >
> > > > Snippet of build error:
> > > > ...lib/librte_eal/linux/eal/eal_memalloc.c: In function ‘alloc_seg_walk’:
> > > > ...lib/librte_eal/linux/eal/eal_memalloc.c:768:12: error: taking
> > > > address of packed member of ‘struct rte_mem_config’ may result in an
> > > > unaligned pointer value [-Werror=address-of-packed-member]
> > > >   768 |  cur_msl = &mcfg->memsegs[msl_idx];
> > > >       |            ^~~~~~~~~~~~~~~~~~~~~~~
> > > >
> > > > Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
> > > >
> > > >
> > > Tested on rhel-7 and fedora-30.
> > > Tested-by: David Marchand <david.marchand@redhat.com>
> > 
> > Applied, thanks
> 
> Its been found that one of the armv7 toolchain treats
> -Wno-address-of-packed-member as unrecognized command line option,
> Hence armv7 build fails on dpdk.org master now. Not sure it is specific to armv7 or compiler?
> 
> Armv7 is not maintained and I don’t think, it has any use case for DPDK.
> If everyone agrees IMO it is better remove the arm 32bit support.
>    
>     arm-buildroot-linux-gnueabihf-gcc -v
>     Using built-in specs.
>     COLLECT_GCC=/opt/armv7-eabihf--glibc--stable-2018.11-1/
>     bin/arm-buildroot-linux-gnueabihf-gcc.br_real
>     COLLECT_LTO_WRAPPER=/opt/armv7-eabihf--glibc--stable-2018.11-1/
>     libexec/gcc/arm-buildroot-linux-gnueabihf/7.3.0/lto-wrapper
>     Target: arm-buildroot-linux-gnueabihf
>     Configured with: ./configure
>     --prefix=/opt/armv7-eabihf--glibc--stable-2018.11-1
>     --sysconfdir=/opt/armv7-eabihf--glibc--stable-2018.11-1/etc
>     --enable-static --target=arm-buildroot-linux-gnueabihf
>     --with-sysroot=/opt/armv7-eabihf--glibc--stable-2018.11-1/
>     arm-buildroot-linux-gnueabihf/sysroot
>     --disable-__cxa_atexit --with-gnu-ld --disable-libssp --disable-multilib
>     --with-gmp=/opt/armv7-eabihf--glibc--stable-2018.11-1
>     --with-mpc=/opt/armv7-eabihf--glibc--stable-2018.11-1
>     --with-mpfr=/opt/armv7-eabihf--glibc--stable-2018.11-1
>     --with-pkgversion='Buildroot 2018.08.1-00003-g576b333'
>     --with-bugurl=http://bugs.buildroot.net/ --disable-libquadmath
>     --enable-tls --disable-libmudflap --enable-threads --without-isl
>     --without-cloog --disable-decimal-float --with-abi=aa
>     pcs-linux --with-cpu=cortex-a9 --with-fpu=vfpv3-d16 --with-float=hard
>     --with-mode=arm --enable-languages=c,c++
>     --with-build-time-tools=/opt/armv7-eabihf--glibc--stable-2018.11-1/
>     arm-buildroot-linux-gnueabihf/bin --enable-shared --disable-libgomp
>     Thread model: posix
>     gcc version 7.3.0 (Buildroot 2018.08.1-00003-g576b333)
> 
>     error log:
> 
>     dpdk.org/lib/librte_eal/linux/eal/eal_vfio_mp_sync.c: At top level:
>     cc1: error: unrecognized command line option
>     ‘-Wno-address-of-packed-member’ [-Werror]
>     cc1: all warnings being treated as errors
> 

Are you sure there is not another error as well? GCC silently ignores flags
like this one normally, but does report them as unrecognised if-and-only-if
another error or warning is given too.

/Bruce