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Doesn't it have a side effect that it modifies default vsyscall behavior? I am guessing the impact of the vsyscall change would be minimal. However, should LASS be disabled by default at least initially to minimize the impact on userspace? A follow-up patch can then enable this by default once the overall impact is clearly known. > If any issues are > found with specific use cases, the CONFIG option > makes it easy to disable. >This sentence is unnecessary. > > +config X86_LASS > + def_bool y > + prompt "Linear Address Space Separation" > + depends on X86_64 && CPU_SUP_INTEL > + help > + Linear Address Space Separation (LASS) is a processor > + feature that mitigates address space layout probes. > + Let's try to be consistent about what LASS is expected to do. This definition is very different from the one in patch 1/7. Also, we should include some information here on how enabling the LASS config option can impact vsyscall behavior. > + if unsure, say Y. > +