[$] Multiple memory classes for address-space isolation

Brendan Jackman has been working to try to get ahead of the next hardware CPUvulnerabilitybefore it gets discovered. In January, he posted the second version ofa patch set that introducesaddress-space isolation (ASI) as a way ofpreventing future CPU vulnerabilities from leaking importantinformation. The core concept is to ensure that data that is not currentlyneeded is not present in memory, so that speculative execution cannot leak it.The work is nowhere near ready to be incorporated into the mainlinekernel - not least of all because it has a large performance impact in itscurrent form - but it is likely to once again be a topic of discussion at the2025Linux Filesystem, Memory Management, and BPF Summit.