On Fri, 11 Oct 2024 20:20:12 +0200 Morten Brørup <m...@smartsharesystems.com> wrote:
> rom: Stephen Hemminger [mailto:step...@networkplumber.org] > > Sent: Friday, 11 October 2024 19.48 > > > > On Fri, 11 Oct 2024 19:36:08 +0200 > > Morten Brørup <m...@smartsharesystems.com> wrote: > > > > > > From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Ferruh Yigit > > > > Sent: Monday, 17 April 2017 16.36 > > > > > > > > clang 4 gives "taking address of packed member may result in an > > > > unaligned pointer value" warnings in a few locations [1]. > > > > > > > > Disabled "-Waddress-of-packed-member" warning for clang >= 4 > > > > > > > > [1] build errors: > > > > .../lib/librte_eal/common/eal_common_memzone.c:275:25: > > > > error: taking address of packed member 'mlock' of class or > > structure > > > > 'rte_mem_config' may result in an unaligned pointer value > > > > [-Werror,-Waddress-of-packed-member] > > > > rte_rwlock_write_lock(&mcfg->mlock); > > > > ^~~~~~~~~~~ > > > > > > > > .../lib/librte_ip_frag/rte_ipv4_reassembly.c:139:31: > > > > error: taking address of packed member 'src_addr' of class or > > structure > > > > 'ipv4_hdr' may result in an unaligned pointer value > > > > [-Werror,-Waddress-of-packed-member] > > > > psd = (unaligned_uint64_t *)&ip_hdr->src_addr; > > > > ^~~~~~~~~~~~~~~~ > > > > > > > > .../lib/librte_vhost/vhost_user.c:1037:34: > > > > error: taking address of packed member 'payload' of class or > > structure > > > > 'VhostUserMsg' may result in an unaligned pointer value > > > > [-Werror,-Waddress-of-packed-member] > > > > vhost_user_set_vring_num(dev, &msg.payload.state); > > > > ^~~~~~~~~~~~~~~~~ > > > > > > > > Signed-off-by: Ferruh Yigit <ferruh.yi...@intel.com> > > > > --- > > > > mk/toolchain/clang/rte.vars.mk | 5 +++++ > > > > 1 file changed, 5 insertions(+) > > > > > > > > diff --git a/mk/toolchain/clang/rte.vars.mk > > > > b/mk/toolchain/clang/rte.vars.mk > > > > index 7749b99..af34c10 100644 > > > > --- a/mk/toolchain/clang/rte.vars.mk > > > > +++ b/mk/toolchain/clang/rte.vars.mk > > > > @@ -79,5 +79,10 @@ include > > > > $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk > > > > # workaround clang bug with warning "missing field initializer" > > for "= > > > > {0}" > > > > WERROR_FLAGS += -Wno-missing-field-initializers > > > > > > > > +# disable packed member unalign warnings > > > > +ifeq ($(shell test $(CLANG_MAJOR_VERSION) -ge 4 && 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 > > > > -- > > > > 2.9.3 > > > > > > > > > > Revisiting an old patch... > > > > > > Maybe the code causing the warnings should have been fixed instead of > > disabling the compiler warning? > > > > > > We would probably handle this differently today... I wonder how many > > warnings it spews out with the warning enabled? > > > > > > -Morten > > > > > > > With gcc-14 and re-enable packed-member and no-zero-length-bounds, lots > > and lots of warnings. > > Thanks for testing this, Stephen. > > It seems to confirm my suspicion... > > Random sampling: > - The warning in lib/ip_frag/rte_ipv4_reassembly.c is caused by using a > temporary variable instead of mempcy(). > - The warning in drivers/bus/ifpga/ifpga_bus.c is caused by a struct being > packed for no good reason. > > It reminds me of compiling the kernel in the good old days... spewed out lots > of new warnings when using a new compiler version. > > This really should be fixed. Disabling compiler warnings because it requires > too much work fixing the bugs is not a valid reason. +1000
