Re: Security is not something that can be patched in later
> such as are those now being discovered in x86 (and by extnension AMD64 instruction set) processors,
The recent exploits (Spectre, Meltdown, Intel's ME problems and so on) have absolutely nothing, at all, to do with the x86 instruction set or with processors that implement the x86 instruction set specifically.
Spectre and Meltdown are to do with speculative execution. A CPU-engineering - completely instruction set agnostic - technique to increase performance. It is bugs in the design and implementation of these features that have caused these issues.
Similar techniques are implemented in PowerPC, SPARC, ARM and other more esoteric (or more niche) architectures.
IBM has been releasing firmware patches to deal with these issues on PowerPC hardware (I work with PowerPC hardware). ARM has as well for their affected (only some of the most recent designs, all older ARM designs prior to about 2 years ago were all in-order execution) chips. I don't deal with SPARC (well, not in 5 or so years) so am unaware of what is specifically happening in that sphere.
These are electronics engineering problems, not x86 problems.
Like with Spectre and Meltdown, Intel's ME issue isn't an x86 instruction set issue. It is an implementation problem with a general purpose - non-instructoin set specific - CPU-design paradigm, embedding an isolated control-processor into the platform.