From: Will Deacon > Sent: 28 March 2018 09:54 ... > > > I don't think so. My reading of memory-barriers.txt says that writeX might > > > expand to outX, and outX is not ordered with respect to other types of > > > memory. > > > > Ugh ? > > > > My understanding of HW at least is the exact opposite. outX is *more* > > ordered if anything, than any other accessors. IO space is completely > > synchronous, non posted and ordered afaik. > > I'm just going by memory-barriers.txt: > > > (*) inX(), outX(): > > [...] > > They are guaranteed to be fully ordered with respect to each other. > > They are not guaranteed to be fully ordered with respect to other types of > memory and I/O operation. A long time ago there was a document from Intel that said that inb/outb weren't necessarily synchronised wrt memory accesses. (Might be P-pro era). However no processors actually behaved that way and more recent docs say that inb/outb are fully ordered. David -- 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
