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Diffstat (limited to 'qemu-deprecated.texi')
| -rw-r--r-- | qemu-deprecated.texi | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi index e6891c3a93..c90b08d553 100644 --- a/qemu-deprecated.texi +++ b/qemu-deprecated.texi @@ -292,3 +292,22 @@ subset of the image. In the future, QEMU will require Python 3 to be available at build time. Support for Python 2 in scripts shipped with QEMU is deprecated. + +@section Backwards compatibility + +@subsection Runnability guarantee of CPU models (since 4.1.0) + +Previous versions of QEMU never changed existing CPU models in +ways that introduced additional host software or hardware +requirements to the VM. This allowed management software to +safely change the machine type of an existing VM without +introducing new requirements ("runnability guarantee"). This +prevented CPU models from being updated to include CPU +vulnerability mitigations, leaving guests vulnerable in the +default configuration. + +The CPU model runnability guarantee won't apply anymore to +existing CPU models. Management software that needs runnability +guarantees must resolve the CPU model aliases using te +``alias-of'' field returned by the ``query-cpu-definitions'' QMP +command. |