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| author | Gustavo Romero <gustavo.romero@linaro.org> | 2024-01-22 21:12:15 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2024-01-26 11:30:49 +0000 |
| commit | 1acf21599859cf2a23a7c9a839f8be7ad555e351 (patch) | |
| tree | 6a9df79c96ef3274e0280c6a21fe919d4d02df58 /docs/system | |
| parent | b0d1021ed948601a7e53e5e30b36a787040d77cf (diff) | |
docs/system/arm/virt.rst: Add note on CPU features off by default
Add a note on CPU features that are off by default in `virt` machines.
Some CPU features will remain off even if a CPU-capable CPU (e.g.,
`-cpu max`) is selected because they require support in both the CPU
itself and in the wider system. Therefore, the user, besides selecting a
CPU that supports such features, must also turn on the feature using a
machine option.
Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
Message-id: 20240122211215.95073-1-gustavo.romero@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs/system')
| -rw-r--r-- | docs/system/arm/virt.rst | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst index c245c52b7a..26fcba00b7 100644 --- a/docs/system/arm/virt.rst +++ b/docs/system/arm/virt.rst @@ -69,6 +69,19 @@ Supported guest CPU types: Note that the default is ``cortex-a15``, so for an AArch64 guest you must specify a CPU type. +Also, please note that passing ``max`` CPU (i.e. ``-cpu max``) won't +enable all the CPU features for a given ``virt`` machine. Where a CPU +architectural feature requires support in both the CPU itself and in the +wider system (e.g. the MTE feature), it may not be enabled by default, +but instead requires a machine option to enable it. + +For example, MTE support must be enabled with ``-machine virt,mte=on``, +as well as by selecting an MTE-capable CPU (e.g., ``max``) with the +``-cpu`` option. + +See the machine-specific options below, or check them for a given machine +by passing the ``help`` suboption, like: ``-machine virt-9.0,help``. + Graphics output is available, but unlike the x86 PC machine types there is no default display device enabled: you should select one from the Display devices section of "-device help". The recommended option |