On Sun, 27 Nov 2022 18:01:26 +0000 Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > > This move is unnecessary, because the cacheline is 16 bytes and the > > buffer is 64 bytes. > > Ah. That particular option hadn't occurred to me (and I'd failed to notice > how big the buffer is :( ). > The marking isn't needed at all then as the allocation is already > guaranteed to be sufficiently aligned. However, maybe that is a bit subtle > and having some sort of marking is useful. You can replace the __cacheline annotation with a comment, that's totally fine. > Curious question though, why is the buffer so big? > Each struct joydata is 8 bytes I think, but the driver only accesses 4 of them. > > Is the hardware putting garbage into the remaining 2 cachelines or is there > something subtle going on? That chip operates on 64-byte units. I don't remember whether the remaining area is garbage or the input bytes or something else. - Lauri
