> Out of curiosity, how expensive is this runtime architechture check? >
I don't think runtime detection is necessary if you compile both library and app for the specific arch. A few ifdef's take care of the selection at compile time. If you want to provide a multiarch binary, I don't know how he does it, but you probably only have to check once when the library is first loaded. You link your app against stub functions and then the detection procedure can point the stubs to the right set of functions (via, i.e., function pointers) and from there on no further check is needed, unless you want to provide support for hot swappable cpu's ;) The penalty in this case is an extra level of indirection (a few stack instructions a jump and a ret) for each call. Well worth the pain, IMO. Luis
