On Sun, Feb 1, 2015 at 3:28 PM, Zac Medico <zmed...@gentoo.org> wrote: > On 02/01/2015 02:39 PM, Matt Turner wrote: >> On Sun, Feb 1, 2015 at 2:17 PM, Michał Górny <mgo...@gentoo.org> wrote: >>> 2. app-emulation/bochs got local USE=3dnow and USE=avx since the flag >>> control support of emulating the two instruction sets rather than using >>> host CPU instruction sets. >> >> Wouldn't it be simpler to use CPU_FLAGS_X86 for these and simply >> disable the emulation code if they're set? That seems better to me. > > CPU_FLAGS is intended to control which machine code instructions are > allowed to be used in the compiled executables. If we use it for > anything else that does not fit this precise definition, then it will be > inconsistent and lead to confusion.
I'd interpreted Michał's statement to mean that bochs would support 3DNow/AVX regardless and that the flag simply determined whether it used the CPU's native support or built emulation code. Looking at the code, I don't believe that is the case. It appears that the flag simply determines whether bochs can execute those instructions at all.
