[$] Generalized address-space isolation

The disclosure of the Meltdown and Spectre vulnerabilities put a spotlighton the risks that come with sharing address spaces too widely. Even if theprotection mechanisms provided by the hardware should prevent access tosensitive data, those vulnerabilities can often be used to leak that data anyway. So, fromthe beginning, mitigation strategies have included reducing the sharing ofaddress spaces, but there is more that could be done and ongoing interest in doing so. Now, thispatch set posted by Junaid Shahid (containing work from Ofir Weisse andinspired by earlierpatches from Alexandre Chartre) shows what would be required to createa general address-space isolation (ASI) mechanism for the kernel.