On Fri, Feb 06, 2004 at 03:29:30PM -0500, Hilmi Ozdoganoglu composed: > > Agreed, the software based approach does not take a significant > performance hit, but the hardware approach is transparent to the user > and does not require recompilation of the source code. Therefore, all > programs can run securely on a machine whether or not they are "compiled > securely" (e.g. legacy software). Not all control flow follows stack logic. So you can't claim backwards compatibility on all programs. What happens if you are compiling continuations, such as a high-performance ML or scheme environment? A scheme environment may often need to keep around call-stacks after they are exited, because call-with-current-continuation can cause them to be reentered again. Similarly, you mention the problem with user-land threads, yet specifically don't solve it (just handwave it a bit). Likewise, what happens on table-blowout? You are using fixed-sized tables, what happens when they fill up (and they WILL fill up. Resources in a CPU should be 0, 1, or infinite, at least from the user's point of view). -- Nicholas C. Weaver nweaver@cs.berkeley.edu
