From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fergus Henderson To: Robert Bernecky Cc: David Edelsohn , John Gilmore , Subject: Re: Esthetics (or worse?) of Secure Pointers Date: Thu, 19 Apr 2001 00:04:00 -0000 Message-id: <20010419170414.A13191@hg.cs.mu.oz.au> References: <200104181703.f3IH3dj06433@phal.cambridge.redhat.com> X-SW-Source: 2001-04/msg00912.html On 18-Apr-2001, Robert Bernecky wrote: > Think of John's proposal as a stepping stone. We introduce a new > architecture (bounded-x86) that lives alongside the existing > x86 architecture. In the fullness of time, everyone buys > into the secure-x86 architecture, we retire the x86 architecture > completely, and everyone lives happily ever after. > > Will this work? I believe that there are strong > engineering and liability reasons that will make it work. ... > John's position, and mine, is that good optimization work should > let us get the cpu time overheads down to acceptable levels. > We are stuck with the memory overhead, but memory is cheaper > every day, so that's probably acceptable, particularly now that > 64-bit architectures are becoming reasonably priced. If you can't avoid significant memory overhead, then due to memory hierarchy effects you're going to have an unavoidable significant time overhead for a lot of applications. Memory may be cheap, but cache is still expensive, and on-chip cache sizes are limited by the technology. CPU speeds are increasing faster than memory speeds, so more and more applications are limited by memory bandwidth. So, although I admire your aims, I don't see the bounded-x86 architecture replacing x86 any time soon. Rather, the two will have to coexist. -- Fergus Henderson | "I have always known that the pursuit | of excellence is a lethal habit" WWW: < http://www.cs.mu.oz.au/~fjh > | -- the last words of T. S. Garp.