Hopefully the new ISA will continue to support tagged memory pointers (capability computing), which can stop many security attacks, https://www.talospace.com/20

Hopefully the new ISA will continue to support tagged memory pointers (capability computing), which can stop many security attacks, https://www.talospace.com/2022/10/power9-and-tagged-memory-and-why-you.html https://www.talospace.com/2022/10/power9-and-tagged-memory-a... & https://www.devever.net/~hl/ppcas https://www.devever.net/~hl/ppcas > IBM's capability-based design is implemented using a hybrid of both hardware and software. The central premise of the design is that you cannot write native code for the platform directly; instead, all programs for the system must be written in an intermediate language which is translated internally (at installation time) to Power ISA machine code by the system's “kernel”. This trusted translator maintains the desired security invariants of the system, just like the modern sandboxed JIT designs used in Java, .NET, JavaScript and WebAssembly, and without relying on hardware memory protection. > In order to support this capability-based OS, IBM implemented an undocumented extension to the Power ISA known as PowerPC AS. This ISA extension provides a memory tagging system which associates one tag bit with every aligned 16 bytes of system memory (a quadword). In a 128-bit pointer, 64 bits are used for the typical memory address; the other half stores a few bits of metadata and is otherwise reserved (the degree of futureproofing is rather extreme). HN discussion (2022), https://news.ycombinator.com/item?id=33381823 https://news.ycombinator.com/item?id=33381823