Re: [dpdk-dev] [PATCH] build: disable gcc 10 zero-length-bounds warning

[David Marchand <david.marchand@redhat.com>]

On Fri, May 15, 2020 at 10:28 AM David Marchand
<david.marchand@redhat.com> wrote:
>
> On Thu, May 14, 2020 at 3:19 PM Kevin Traynor <ktraynor@redhat.com> wrote:
> >
> > gcc 10 issues warnings about the use of rearm_data marker
> > from struct rte_mbuf.
> >
> > e.g.
> > ../drivers/net/enic/enic_rxtx_vec_avx2.c: In function ‘rx_one’:
> > ../drivers/net/enic/enic_rxtx_vec_avx2.c:21:2:
> > warning:
> > array subscript 0 is outside the bounds of an interior zero-length array
> > ‘RTE_MARKER64’ {aka ‘long unsigned int[0]’} [-Wzero-length-bounds]
> >    21 |  *(uint64_t *)&mb->rearm_data = enic->mbuf_initializer;
> >       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > In file included from ../lib/librte_mbuf/rte_mbuf.h:45,
> >                  from ../drivers/net/enic/enic_rxtx_vec_avx2.c:6:
> > ../lib/librte_mbuf/rte_mbuf_core.h:484:15:
> > note: while referencing ‘rearm_data’
> >   484 |  RTE_MARKER64 rearm_data;
> >       |
> >
> > Disable this warning for gcc 10 in order to allow v20.05 to build
> > without changes to struct rte_mbuf.
> >
> > Bugzilla ID: 396
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
> >
> > ---
> > Sending as per discussion at this mornings release meeting:
> > http://inbox.dpdk.org/dev/2980eb50-124c-9da8-9927-0678081b652b@intel.com/
> >
> > Reference to Gavin's patch:
> > http://inbox.dpdk.org/dev/CAJFAV8yL2GvEJtTXOLk6o0eXHi4CpZmqCoRsfN2WcDe_ju1C8A@mail.gmail.com/#t
> > ---
> >  config/meson.build           | 4 ++++
> >  mk/toolchain/gcc/rte.vars.mk | 5 +++++
> >  2 files changed, 9 insertions(+)
> >
> > diff --git a/config/meson.build b/config/meson.build
> > index a1c38c053..43ab11310 100644
> > --- a/config/meson.build
> > +++ b/config/meson.build
> > @@ -209,4 +209,8 @@ warning_flags = [
> >         '-Wno-missing-field-initializers'
> >  ]
> > +if cc.get_id() == 'gcc' and cc.version().version_compare('>=10.0')
> > +# FIXME: Bugzilla 396
> > +       warning_flags += '-Wno-zero-length-bounds'
> > +endif
> >  if not dpdk_conf.get('RTE_ARCH_64')
> >  # for 32-bit, don't warn about casting a 32-bit pointer to 64-bit int - it's fine!!
> > diff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk
> > index f19305e49..928f0e083 100644
> > --- a/mk/toolchain/gcc/rte.vars.mk
> > +++ b/mk/toolchain/gcc/rte.vars.mk
> > @@ -82,4 +82,9 @@ WERROR_FLAGS += -Wno-uninitialized
> >  endif
> >
> > +ifeq ($(shell test $(GCC_VERSION) -ge 100 && echo 1), 1)
> > +# FIXME: Bugzilla 396
> > +WERROR_FLAGS += -Wno-zero-length-bounds
> > +endif
> > +
> >  HOST_WERROR_FLAGS := $(WERROR_FLAGS)
> >
> > --
> > 2.21.3
> >
>
> Reviewed-by: David Marchand <david.marchand@redhat.com>

No objection on this patch, so I'll proceed and merge it for rc3.


-- 
David Marchand