diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/system/arm/sbsa.rst | 35 |
1 files changed, 26 insertions, 9 deletions
diff --git a/docs/system/arm/sbsa.rst b/docs/system/arm/sbsa.rst index bca6160..2bf22a1 100644 --- a/docs/system/arm/sbsa.rst +++ b/docs/system/arm/sbsa.rst @@ -1,12 +1,16 @@ 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 -<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. +The ``sbsa-ref`` board intends to look like real hardware (while the ``virt`` +board is a generic board platform that doesn't match any real hardware). + +The hardware part is defined by two specifications: + + - `Base System Architecture <https://developer.arm.com/documentation/den0094/>`__ (BSA) + - `Server Base System Architecture <https://developer.arm.com/documentation/den0029/>`__ (SBSA) + +The `Arm Base Boot Requirements <https://developer.arm.com/documentation/den0044/>`__ (BBR) +specification defines 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. @@ -35,16 +39,29 @@ 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). +Note +'''' + +QEMU provides the guest EL3 firmware with minimal information about hardware +platform using minimalistic devicetree. This is not a Linux devicetree. It is +not even a firmware devicetree. + +It is information passed from QEMU to describe the information a hardware +platform would have other mechanisms to discover at runtime, that are affected +by the QEMU command line. + +Ultimately this devicetree may be replaced by IPC calls to an emulated SCP. + DeviceTree information '''''''''''''''''''''' -The devicetree provided by the board model to the firmware is not intended -to be a complete compliant DT. It currently reports: +The devicetree reports: - CPUs - memory - platform version - GIC addresses + - NUMA node id for CPUs and memory Platform version '''''''''''''''' @@ -70,4 +87,4 @@ Platform version changes: GIC ITS information is present in devicetree. 0.3 - The USB controller is an XHCI device, not EHCI + The USB controller is an XHCI device, not EHCI. |