diff options
| author | Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org> | 2023-05-31 19:18:34 +0200 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2023-06-19 14:41:57 +0100 |
| commit | ff49fb950dd89da21b6ab77f39d7bd5be2a63542 (patch) | |
| tree | 55460626e08d12cb69f54bbe431529bc128af7ca /docs | |
| parent | bd96e10071e4d44eea9b9c8888ed12d2f9d8fae9 (diff) | |
docs: sbsa: document board to firmware interface
We plan to add more hardware information into DeviceTree to limit amount
of hardcoded values in firmware.
Signed-off-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Message-id: 20230531171834.236569-1-marcin.juszkiewicz@linaro.org
[PMM: fix format nits, add text about platform version fields from
a comment in the C source file]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/system/arm/sbsa.rst | 38 |
1 files changed, 31 insertions, 7 deletions
diff --git a/docs/system/arm/sbsa.rst b/docs/system/arm/sbsa.rst index 016776aed8..f571fe645e 100644 --- a/docs/system/arm/sbsa.rst +++ b/docs/system/arm/sbsa.rst @@ -6,12 +6,7 @@ any real hardware the ``sbsa-ref`` board intends to look like real hardware. The `Server Base System Architecture <https://developer.arm.com/documentation/den0029/latest>`_ defines a minimum base line of hardware support and importantly how the firmware -reports that to any operating system. It is a static system that -reports a very minimal DT to the firmware for non-discoverable -information about components affected by the qemu command line (i.e. -cpus and memory). As a result it must have a firmware specifically -built to expect a certain hardware layout (as you would in a real -machine). +reports that to any operating system. It is intended to be a machine for developing firmware and testing standards compliance with operating systems. @@ -19,7 +14,7 @@ standards compliance with operating systems. Supported devices """"""""""""""""" -The sbsa-ref board supports: +The ``sbsa-ref`` board supports: - A configurable number of AArch64 CPUs - GIC version 3 @@ -30,3 +25,32 @@ The sbsa-ref board supports: - Bochs display adapter on PCIe bus - A generic SBSA watchdog device + +Board to firmware interface +""""""""""""""""""""""""""" + +``sbsa-ref`` is a static system that reports a very minimal devicetree to the +firmware for non-discoverable information about system components. This +includes both internal hardware and parts affected by the qemu command line +(i.e. CPUs and memory). As a result it must have a firmware specifically built +to expect a certain hardware layout (as you would in a real machine). + +DeviceTree information +'''''''''''''''''''''' + +The devicetree provided by the board model to the firmware is not intended +to be a complete compliant DT. It currently reports: + + - CPUs + - memory + - platform version + - GIC addresses + +The platform version is only for informing platform firmware about +what kind of ``sbsa-ref`` board it is running on. It is neither +a QEMU versioned machine type nor a reflection of the level of the +SBSA/SystemReady SR support provided. + +The ``machine-version-major`` value is updated when changes breaking +fw compatibility are introduced. The ``machine-version-minor`` value +is updated when features are added that don't break fw compatibility. |