asm_safe
rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));
rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_tmp));
rc = asm_safe("fxrstor %[fx]", : [fx] "m"(fx_state));
rc = asm_safe("fwait");