On Thu, May 2, 2019 at 4:13 PM Reshma Pattan <reshma.pat...@intel.com> wrote:
> gcc 9 on Fedora 30 gives an error > "taking address of packed member may result in an > unaligned pointer value" for -Waddress-of-packed-member. > > Report it as warning instead of error to fix the build. > > Snippet of build before fix > ...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]; > | ^~~~~~~~~~~~~~~~~~~~~~~ > > Snippet of build after fix > ..lib/librte_eal/linux/eal/eal_memory.c: In function ‘remap_segment’: > ..lib/librte_eal/linux/eal/eal_memory.c:685:9: warning: taking address > of packed member of ‘struct rte_mem_config’ may result in an unaligned > pointer value [-Waddress-of-packed-member] > 685 | msl = &mcfg->memsegs[msl_idx]; > > Signed-off-by: Reshma Pattan <reshma.pat...@intel.com> > --- > mk/toolchain/gcc/rte.vars.mk | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk > index d8b99faf6..61032bbbc 100644 > --- a/mk/toolchain/gcc/rte.vars.mk > +++ b/mk/toolchain/gcc/rte.vars.mk > @@ -87,5 +87,9 @@ WERROR_FLAGS += -Wimplicit-fallthrough=2 > WERROR_FLAGS += -Wno-format-truncation > endif > > +#Report "taking address of packed member may result > +#in an unaligned pointer value" issues as warnings. > +WERROR_FLAGS += -Wno-error=address-of-packed-member > + > export CC AS AR LD OBJCOPY OBJDUMP STRIP READELF > export TOOLCHAIN_CFLAGS TOOLCHAIN_LDFLAGS TOOLCHAIN_ASFLAGS > -- > 2.21.0 > > No, you can't do this unconditionally. Looked at clang (in make build system) and meson (globally) and those completely disable the warning. $ git grep address-of-packed-member origin/master -- origin/master:config/meson.build: '-Wno-address-of-packed-member' origin/master:mk/toolchain/clang/rte.vars.mk:WERROR_FLAGS += -Wno-address-of-packed-member It should be something like (untested): @@ -87,5 +87,10 @@ WERROR_FLAGS += -Wimplicit-fallthrough=2 WERROR_FLAGS += -Wno-format-truncation endif +# disable packed member unalign warnings +ifeq ($(shell test $(GCC_VERSION) -ge 90 && echo 1), 1) +WERROR_FLAGS += -Wno-address-of-packed-member +endif + export CC AS AR LD OBJCOPY OBJDUMP STRIP READELF export TOOLCHAIN_CFLAGS TOOLCHAIN_LDFLAGS TOOLCHAIN_ASFLAGS -- David Marchand
