On Tue, 2018-03-27 at 08:12 -0600, Jason Gunthorpe wrote: > > I have been converting wmb+writel to wmb+writel_relaxed. (About 30 patches) > > > > I will have to just remove the wmb and keep writel, then repost. > > Okay, but before you do that, can we get a statement how this works > for WC? > > Some of these writels are to WC memory, do they need the wmb()?!? This is an issue as we don't have well defined semantics for WC. At this point, I would suggest staying away from that (ie, not changing them). We need to look into it. I know for example that on powerpc I cannot give you any weaker semantic on WC for writel (I have to put a full sync in there), but I am trying to see if I can make writel_relaxed both work with the existing semantics and provide combining. But it's not yet a given (our weaker IO barrier, eieio, isn't architecturally defined to do anything on G=0 space, looking with the HW guys at what the HW actually does). Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
