It's much simpler and much faster to make a chunk of code completely isolated in user space by masking the addresses it reads/writes to. For example, masking wi

It's much simpler and much faster to make a chunk of code completely isolated in user space by masking the addresses it reads/writes to. For example, masking with 0xFFFF is the same as doing modulo 16. Add another bit to the mask and you're doing modulo 32, and so on. That's why I think the block must be not only contiguous, but also aligned. I may be wrong about the alignment now that I think about it. But the contiguous part is clear.