>On Tue, Mar 31, 2015 at 11:23:32PM +0100, Mark Kavanagh wrote: >> DPDK 2.0 contains an updated implementation of rte_memcopy, which >> leverages SSE and AVX instrinsics. In versions of GCC <= 4.8.2, it >> has been observed that the relevant instrinsics are not defined in >> gcc headers, resulting in compile-time errors. >> This issue is resolved by enabling the 'mssse3' flag at compile time; >> however, it's not possible to pass an additional flag via the command >> line without overwriting an existing compiler variable. >> >> Introduce an additonal configuration option to resolve this. >> >> Signed-off-by: Mark Kavanagh <mark.b.kavan...@intel.com> > >What's wrong with setting CFLAGS on the "configure" or "make" command >line? This is the standard way to do this with Automake and Autoconf. >
Sure. However, setting CFLAGS on the command line overwrites any values CFLAGS has attained via the 'configure' step. The most obvious symptom of this is significantly degraded performance, due to the fact that the optimization flags passed to CFLAGS during 'configure' are overwritten by the command line value of CFLAGS. >We should certainly not introduce a configure option for every single >possible compiler flag. Agreed; given the precedent set by OVS_ENABLE_WERROR, I figured that this was the convention. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
