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| -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. |