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

[Fernando Rodriguez]

On Monday, March 23, 2015 6:48:39 PM Mike Gilbert wrote:
> On Mon, Mar 23, 2015 at 6:41 PM, Fernando Rodriguez
> <frodriguez.developer@×××××××.com> wrote:
> > On Monday, March 23, 2015 6:18:46 PM Mike Gilbert wrote:
> >> On Mon, Mar 23, 2015 at 9:51 PM, Walter Dnes <waltdnes@××××××××.org>
wrote:
> >> > On Sun, Mar 22, 2015 at 09:25:53PM -0400, Fernando Rodriguez wrote
> >> >
> >> >> I guess gcc devs are careful when using the model numbers (Intel
> >> >> lists 3 for Atoms, gcc uses only two so that may account for the
> >> >> models I mentioned) but the chance of error is there. The -mno-xxx
> >> >> flags would safeguard against it.
> >> >
> >> >   I have one of the earliest Atom chips.  Some people have a hard time
> >> > believing this, but it's a 32-bit-only chip;  a couple of lines from
> >> > /proc/cpuinfo
> >> >
> >> > model name      : Intel(R) Atom(TM) CPU Z520   @ 1.33GHz
> >> > address sizes   : 32 bits physical, 32 bits virtual
> >> >
> >> >   Intel gives the CPU's specs at...
> >> >
> >> > http://ark.intel.com/products/35466/Intel-Atom-Processor-Z520-512K-Cache-1_33-GHz-533-MHz-FSB
> >> >
> >> > ...where it specifically says...
> >> >
> >> > Intel 64 # No
> >> >
> >> >   I want to make absolutely certain that "illegal instructions" are not
> >> > compiled for it.
> >>
> >> You will probably need to add -m32 to CFLAGS to avoid building 64-bit
> >> objects on the 64-bit machine.
> >>
> >
> > Your CPU is an example of what I'm saying, not just because it doesn't
have 64
> > bit extensions but because it doesn't have MMX (at least according to the
> > specs) and according to the GCC manual -march=atom means: "Intel Atom CPU
with
> > 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set
> > support." So I guess it's more common than I thought.
> >
> > So you may also want to add -mno-mmx to be sure. GCC does check for mmx
but it
> > doesn't not use it on the output (probably a bug?).
> >
>
> It's much more likely that Intel's website doesn't bother including
> MMX because it is so damn old that nobody cares.
>
> /proc/cpuinfo would be a more reliable source of data.
>

I agree that's very likely, that's why I said if the specs are right...
This one doesn't list any SIMD extensions at all:
http://ark.intel.com/products/85475/Intel-Atom-x7-Z8700-Processor-2M-Cache-up-to-2_40-GHz


-- 
Fernando Rodriguez