On Monday, March 23, 2015 6:48:39 PM Mike Gilbert wrote: > On Mon, Mar 23, 2015 at 6:41 PM, Fernando Rodriguez > <[email protected]> wrote: > > On Monday, March 23, 2015 6:18:46 PM Mike Gilbert wrote: > >> On Mon, Mar 23, 2015 at 9:51 PM, Walter Dnes <[email protected]> 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
