Arm Server Base System Architecture Reference board (``sbsa-ref``) ================================================================== While the ``virt`` board is a generic board platform that doesn't match any real hardware the ``sbsa-ref`` board intends to look like real hardware. The `Server Base System Architecture `_ defines a minimum base line of hardware support and importantly how the firmware reports that to any operating system. It is intended to be a machine for developing firmware and testing standards compliance with operating systems. Supported devices """"""""""""""""" The ``sbsa-ref`` board supports: - A configurable number of AArch64 CPUs - GIC version 3 - System bus AHCI controller - System bus EHCI controller - CDROM and hard disc on AHCI bus - E1000E ethernet card on PCIe bus - 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.