CPUTYPE=native handling

[Alexander Best]

On Tue Nov  8 11, Dimitry Andric wrote:
> On 2011-11-08 01:25, Alexander Best wrote:
> > i've seen dozens of issues, where people set CPUTYPE=native. although this
> > works in a lot of cases, it doesn't in others. why don't we simply add
> > something like
> > 
> > . if ${CPUTYPE} == "native"
> > .  error "bla"
> > . endif
> > 
> > in share/mk/bsd.cpu.mk for now? or at least for the archs, where "native" is
> > known to cause problems.
> 
> What does this solve?  Don't you think it is better to try to fix the
> actual problems?  Some people like being able to optimize for their
> specific CPU, however much you can shoot yourself in the foot with it.

just wanted to report that i found an issue with CPUTYPE "native". simply do
the following on amd64 (i tested this on ref9-amd64.freebsd.org):

make.conf:
CPUTYPE ?= native
CFLAGS = -O2 -pipe -fno-strict-aliasing -funroll-loops -fno-builtin
KERNCONF = GENERIC

now 'make buildworld' and enjoy the signal 11. ;)

setting CPUTYPE to nocona or commenting it out lets 'mak buildworld' succeed.

cheers.
alex

there's a problem report for this already:

http://www.freebsd.org/cgi/query-pr.cgi?pr=gnu/149712

> 
> I haven't seen any consistent bug reports yet, just a lot of complaints
> that indicate a rather high probability of PEBKAC.
> 
> And just to counter the nay-saying, I compiled a number of boxes with
> clang -march=native (mostly of the Xeon/i7 variant) and I haven't seen
> any problems at all.