* Peter Maydell: > Apart from the QEMU/KVM specific CPU models, why is this something > we should be documenting rather than, say, the people specifying > what the ABI compatiblity levels are ?
The psABI only cares about userspace, and the specification there deliberately excludes CPU features used in cryptography blocks, and features that seem unstable and likely to be disabled in firmware or future microcode updates. This seemed a good trade-off for the psABI because in userspace, run-time detection is still available, to access additional CPU features not available as part of the target x86-64 level at build time. This doesn't really work for virtualization, which also has to decide what to do with CPU features not relevant to userspace. And a decision to exclude features is final in the sense that guests cannot use the feature at all because run-time detection shows it is as unavailable. This is why a 1:1 copy of the userspace levels to virtualized machine models is not possible, I think. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill
