The gcc mtune documentation is ambiguous about Intel Atom cpus; it doesn't clearly explain how 32-bit Atom cpus should be handled: "atom: Intel Atom CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support" ( https://gcc.gnu.org/onlinedocs/gcc-4.5.3/gcc/i386-and-x86_002d64-Options.html ) While most of the Intel Atom processors are 64-bit, there are two 32-bit models, the Diamondville N270 and N280. So does choosing "-mtune=atom" only give you 64-bit code? If so, should we add a note to choose an alternate "-mtune=XXX" for 32-bit Atom processors? If "-mtune=atom" is compatible with 32-bit processors (I guess by adding "-m32" ?), we should amend the documentation so it doesn't lead you to believe that ALL Atom processors are 64-bit. - Matthew Whitehead
