"Karl O. Pinc" <k...@meme.com> writes: > Doesn't the kernel care whether userspace has direct access to > hardware?
If userspace has the right privileges, then no. The X server is an example of this. > Seems to me that the kernel does more than abstract hardware, it also > protects hardware by managing concurrency and so forth and protects > the entire system by keeping users from doing things with hardware > that interfere with other processes. (E.g. bypassing the VM and doing > DMA direct into somebody else's address space.) Direct userspace > access to hardware violates these principals. Why would HW crypto > accelerators be different and not require kernel mediation? Kernel mediation doesn't require DMA to go through kernel space. That's what zero copy is all about. /Benny
