Re: [gentoo-user] Will a 64-bit-no-multilib machine cross-compile 32-bit code?

[Fernando Rodriguez <frodriguez.developer@outlook.com>]

On Sunday, March 22, 2015 10:03:01 AM Mike Gilbert wrote:
> On Sat, Mar 21, 2015 at 3:52 PM, Fernando Rodriguez
> <frodriguez.developer@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 <waltdnes@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.
> 

Thanks for explaining.

-- 
Fernando Rodriguez