On 10/17/2013 05:39 PM, Will Deacon wrote: > On Wed, Oct 16, 2013 at 06:11:45PM +0100, Jiang Liu wrote: >> On 10/16/2013 07:46 PM, Will Deacon wrote: >>> >>>> + } else { >>>> + insn = aarch64_insn_gen_nop(); >>> >>> You could make the code more concise by limiting your patching ability to >>> branch immediates. Then a nop is simply a branch to the next instruction (I >>> doubt any modern CPUs will choke on this, whereas the architecture requires >>> a NOP to take time). >> I guess a NOP should be more effecient than a "B #4" on real CPUs:) > > Well, I was actually questioning that. A NOP *has* to take time (the > architecture prevents implementations from discaring it) whereas a static, > unconditional branch will likely be discarded early on by CPUs with even > simple branch prediction logic. I naively thought "NOP" is cheaper than a "B" :( Will use a "B #1" to replace "NOP".
Thanks! Gerry > > Will > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/