Mill Computing, Inc. Forums The Mill Architecture Security Reply To: Security

Ivan Godard
Post count: 689

Actually there is hardware virtual memory on the Mill, and paging and all the rest, and the virtual-to-physical translation, page traps and so on take place in the TLB in a quite ordinary way. It’s just that the TLB is in an unusual place in the architecture, after rather than before the caches as seen from the core, and protection is divorced from paging and moved to a different unit.

Well, that’s not quite true: there are some extras in the Mill MMU: virtual zero (described in the talk), and some NYF dealing with Unix fork(). But it’s mostly true.

As for embedded work, the problem with a smaller address space footprint is aliasing. If an embedded application had sufficiently small address space needs that everything would fit in 32 bits with no memory mapping/aliasing the the Mill single-address-space model would work; it would be a full normal Mill with an implied (and ot represented) zero in the high-order word of pointers. Note that you would still want a PLB. Whether the market for a 32-bit-no-MMU Mill is big enough to justify the work is unknown.

Which brings me to your market questions. The Mill innovations tend to interlock righter tightly, so it is difficult to pull just one out and apply it to some other architecture. For example, you could pull Mill split-stream encoding out and apply it to a VLIW to be able to decode 30 ops per cycle like the Mill does. But without things like the Belt in the execution engine you wouldn’t be able to execute all the ops you decoded. And so on. We’re not opposed to licensing, and would take NRE contracts to port some of the ideas to other machines, but we see the opportunities as being rather limited. We feel that more likely we will sell hard macros of full Mills into SOCs.

In contrast, we are actively interested in partners for the Mill itself. We know that large buyers will demand second-source availability, which means a license/partner. In addition there are specialized markets – rad-hardened, for example – where the existing vendors have expertise we will never have and a license seems the way to go. It’s the usual business story though – nobody wants to be the first to stick their neck out about a new architecture, but as soon as one bites everybody will be at our door.

To which we will say: we are not an ARM with a license-based business model, so it’s going to be first-come-first-served.