On 6/7/19 9:35 AM, Andy Lutomirski wrote: > One might reasonably wonder why this state is privileged in the first > place and, given that, why we’re allowing it to be written like > this. I think it's generally a good architectural practice to make things like this privileged. They're infrequent so can survive the cost of a trip in/out of the kernel and are a great choke point to make sure the OS is involved. I wish we had the same for MPX or pkeys per-task "setup".