diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2024-01-09 17:08:34 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2024-01-15 17:12:22 +0000 |
| commit | 8cf1da729170b7cc47ebaca46912a4f37675dc95 (patch) | |
| tree | a6f35c5bb926a0d126f500c80592b69cd8748bb3 /docs | |
| parent | 71e269fb7bd14b5e4b055b6978a4ab193e11ee8e (diff) | |
docs/system/arm/virt.rst: Improve 'highmem' option docs
Improve the 'highmem' option docs to note that by default we assume
that a 32-bit kernel on an LPAE-capable CPU has LPAE enabled, and
what the consequences are.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-id: 20240109170834.1387457-1-peter.maydell@linaro.org
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/system/arm/virt.rst | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst index 7c4c80180c..c245c52b7a 100644 --- a/docs/system/arm/virt.rst +++ b/docs/system/arm/virt.rst @@ -96,7 +96,13 @@ mte highmem Set ``on``/``off`` to enable/disable placing devices and RAM in physical address space above 32 bits. The default is ``on`` for machine types - later than ``virt-2.12``. + later than ``virt-2.12`` when the CPU supports an address space + bigger than 32 bits (i.e. 64-bit CPUs, and 32-bit CPUs with the + Large Physical Address Extension (LPAE) feature). If you want to + boot a 32-bit kernel which does not have ``CONFIG_LPAE`` enabled on + a CPU type which implements LPAE, you will need to manually set + this to ``off``; otherwise some devices, such as the PCI controller, + will not be accessible. compact-highmem Set ``on``/``off`` to enable/disable the compact layout for high memory regions. |