Re: Zero copy?
If my grey cells haven't gone too grey then I think HP-UX implemented zero copy network stacks about 18 years ago. I suspect that it was just zero copy inside the kernel but still copied in and out of user space from the system call entry/exit functions. HP-UX wasn't the only one. The 2007 implementation of sendfile should allow sharing of the buffers between user space and kernel space using page aliasing. I don't know the intricacies of the x86 MMU but I guess it isn't using a global VAS and so this should be easier.