Isn't there a higher risk of data loss, if your "hard drive" is 100% memory mapped - all it would take is one buggy kernel driver writing to an invalid pointer or memset'ing the whole thing to 0?
well, the same is true now as well right ? for example, a buggy driver can override a buffer-cache pointer with something else, and then you are hosed. if you are playing in the kernel-land and not careful enough, you are courting disaster...
True, but if it overruns a buffer, it still needs to maintain a valid SCSI/ATAPI/whatever command packet format and submit the packet to the controller with repeatedly increasing block numbers - that's a lot of instructions, while something that clears the entire address space could probably be done in 1-2 assembly instructions (mov rcx, -1; rep stosq)