On Sat, Mar 21, 2015 at 3:52 PM, Fernando Rodriguez <frodriguez.develo...@outlook.com> wrote: > On Saturday, March 21, 2015 8:46:10 AM Mike Gilbert wrote: >> On Thu, Mar 19, 2015 at 12:20 AM, Walter Dnes <waltd...@waltdnes.org> wrote: >> > CFLAGS="-O2 -march=atom -mno-cx16 -msahf -mmovbe -mno-aes -mno-pclmul - > mno-popcnt -mno-abm -mno-lwp -mno-fma -mno-fma4 -mno-xop -mno-bmi -mno-bmi2 - > mno-tbm -mno-avx -mno-avx2 -mno-sse4.2 -mno-sse4.1 -mno-lzcnt -mno-rtm -mno- > hle -mno-rdrnd -mno-f16c -mno-fsgsbase -mno-rdseed -mno-prfchw -mno-adx -mfxsr > -mno-xsave -mno-xsaveopt --param l1-cache-size=24 --param l1-cache-line- > size=64 --param l2-cache-size=512 -mtune=atom -fstack-protector -mfpmath=sse - > fomit-frame-pointer -pipe -fno-unwind-tables -fno-asynchronous-unwind-tables" >> > >> > Is that correct (assuming that's my output)? >> > >> >> I should warn you against including all of those -mno-xxx flags. This >> has been known to break the build process for packages like chromium, >> which always wants to build with SSE4 support and toggles it off at >> runtime. Passing -mno-sse4.1 causes a build failure as it tries to use >> macros that are not defined. >> > > Isn't it possible that removing it for all packages would cause a more subtle > problem with another faulty ebuild (like a program crashing due to an illegal > instruction)?
Passing -march=atom should be sufficient to ensure that you don't get any illegal instructions. The -mno-XXX flags are redundant, and MOSTLY harmless. In the case of chromium, the build system adds -msse4.1 for specific files (just the ones using SSE4.1 instructons). When you have -mno-sse4.1, this takes precedence and the build fails.
