system/arm/cpu-features.rst

6 corresponding boolean CPU proprieties that, when enabled, indicate
19 support the AArch32 CPU feature, which may be enabled by disabling the
56 enabled, as they are all ``true``.  (The ``sve<N>`` CPU features are all
81        "'aarch64' feature cannot be disabled unless KVM is enabled and 32-bit EL1 is supported"
127 seattle host, but mostly if KVM is enabled the ``host`` CPU type must be
133 do if we want to launch guests without all the host's CPU features enabled.
138 When KVM is enabled, only the ``max``, ``host``, and current CPU type may be
142 above, the ``cortex-a57`` CPU type is also valid when KVM is enabled.
147 some time.  Additionally, if the KVM-enabled QEMU instance running on a
155 given CPU type, then they may be selectively enabled or disabled on the
175 The features' CPU properties are only available when KVM is enabled and
177 enabled, and disabled in the same way as other CPU features.  Below is
182   the virtual time adjustment is enabled (vtime is not *not* adjusted).
184   When virtual time adjustment is enabled each time the VM transitions
198   Since v5.2, kvm-steal-time is enabled by default when KVM is
199   enabled, the feature is supported, and the guest is 64-bit.
201   When kvm-steal-time is enabled a 64-bit guest can account for time
217   When ``pauth`` is enabled, select the QEMU implementation defined algorithm.
220   When ``pauth`` is enabled, select the architected QARMA3 algorithm.
222 Without either ``pauth-impdef`` or ``pauth-qarma3`` enabled,
238 to be enabled by default, then, in order to avoid overly verbose command
246   1) At least one vector length must be enabled when ``sve`` is enabled.
248   2) If a vector length ``N`` is enabled, then, when KVM is enabled, all
249      smaller, host supported vector lengths must also be enabled.  If
250      KVM is not enabled, then only all the smaller, power-of-two vector
251      lengths must be enabled.  E.g. with KVM if the host supports all
253      is enabled, the 128-bit vector length, 256-bit vector length, and
254      384-bit vector length must also be enabled. Without KVM, the 384-bit
257   3) If KVM is enabled then only vector lengths that the host CPU type
258      support may be enabled.  If SVE is not supported by the host, then
259      no ``sve*`` properties may be enabled.
265      are enabled or disabled is irrelevant to the guest, as the entire
269      then the guest will get only the enabled lengths.  If no ``sve=on``
270      is provided and there are explicitly enabled vector lengths, then
273   2) If SVE is enabled (``sve=on``), but no ``sve<N>`` CPU properties are
274      provided, then all supported vector lengths are enabled, which when
279   3) If SVE is enabled, then an error is generated when attempting to
280      disable the last enabled vector length (see constraint (1) of "SVE
283   4) If one or more vector lengths have been explicitly enabled and at
284      least one of the dependency lengths of the maximum enabled length
288   5) When KVM is enabled, if the host does not support SVE, then an error
292   6) When KVM is enabled, if the host does support SVE, then an error is
299      disabled but the default for any unspecified lengths remains enabled.
300      When KVM is not enabled, disabling a power-of-two vector length also
302      When KVM is enabled, then disabling any supported vector length also
307      are enabled and all unspecified lengths default to disabled, except
309      Dependencies and Constraints", which will even be auto-enabled if
310      they were not explicitly enabled.
329   3) When KVM is enabled, implicitly enable all host CPU supported vector
340      uninitialized lengths (128, 256, and 384) defaulting to enabled::
349      lengths are required for the 512-bit vector length to be enabled,
350      then allow them to be auto-enabled::
392      lengths supported by ``max`` defaulting to enabled
406 If the default length is larger than the maximum vector length enabled,
421 SVE mode is enabled.
425 At least one vector length must be enabled when ``sme`` is enabled,
440 than the maximum vector length enabled, the actual vector length will
449 The feature is enabled by the CPU property ``x-rme``, with the ``x-``