On Sat, Dec 22, 2012 at 05:51:08PM +0200, Avi Kivity wrote: > On Sat, Dec 22, 2012 at 5:45 PM, Avi Kivity <avi.kivity@xxxxxxxxx> wrote: > > On Sat, Dec 22, 2012 at 5:39 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote: > >> On Sat, Dec 22, 2012 at 05:28:00PM +0200, Avi Kivity wrote: > >>> On Sat, Dec 22, 2012 at 5:11 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote: > >>> >> #define X2(x...) x, x > >>> >> #define X3(x...) X2(x), x > >>> >> @@ -1584,6 +1585,9 @@ static int writeback(struct x86_emulate_ctxt *ctxt) > >>> >> { > >>> >> int rc; > >>> >> > >>> >> + if (ctxt->d & NoWrite) > >>> >> + return X86EMUL_CONTINUE; > >>> >> + > >>> > Why not make it Dst flag and set dst.type to OP_NONE during decoding > >>> > instead of this special case? > >>> > >>> My thinking was to eventually convert everything to NoWrite, then it's > >>> not a special case. But your approach works too, I can change it if > >>> you like. We'll have an if () either way though. > >> But meanwhile we will have two different ways to disable writeback. When > >> all instructions will be marked with NoWrite we can switch it easily if > >> we want. Also some instruction can disable writeback conditionally. cmov is one > >> (and may be only) of them. > > > > Makes sense, will update for the next iteration. > > Actually that doesn't work. x86_emulate_insn() needs dst.type in order > to fetch the operand. True :(. Actually if we will move from OP_NONE to NoWrite we can drop saved_dst_type hack from x86_emulate_insn. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html