Document the requirements for secure firmware to implement PSCI, particularly in regard to multiprocessor CPU startup protocol. PSCI is by far the preferred solution, but make allowance for the other existing methods.
Signed-off-by: Grant Likely grant.likely@arm.com --- source/ebbr.rst | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)
diff --git a/source/ebbr.rst b/source/ebbr.rst index 700feba..59af3c9 100644 --- a/source/ebbr.rst +++ b/source/ebbr.rst @@ -309,6 +309,25 @@ the aid of the Operating System. .. note:: This normally requires dedicated storage for UEFI variables that is not directly accessible from the Operating System.
+****************************** +Priviledged or Secure Firmware +****************************** + +Multiprocessor Startup Protocol +=============================== +Firmware resident in Trustzone EL3 must implement and conform to the +Power State Coordination Interface specification[PSCI_]. + +Platforms without EL3 must implement one of: + +- PSCI at EL2 (leaving only EL1 available to an operating system) +- MP Startup for Arm[MPSTART_] (ACPI Parking Protocol) on an ACPI platform +- Linux AArch64 spin tables[LINUXA64BOOT_] on a Devicetree platform + +However, the MP Startup and Spintable protocols are strongly discouraged. +Future versions of this specification will only allow PSCI, and PSCI should +be implemented in all new designs. + **************************************** APPENDIX A - Required UEFI Boot Services **************************************** @@ -542,6 +561,12 @@ EFI_ISCSI_INITIATOR_NAME_PROTOCOL 16.2 .. [DTSPEC] `Devicetree specification v0.2 https://github.com/devicetree-org/devicetree-specification/releases/tag/v0.2`_, `Devicetree.org https://devicetree.org`_ +.. [LINUXA64BOOT] `Linux Documentation/arm64/booting.txt + https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/Documentation/arm64/booting.txt`_, + Linux kernel +.. [MPSTART] `MP Startup for Arm + https://acpica.org/sites/acpica/files/MP%20Startup%20for%20ARM%20platforms.doc`_, + 20 December 2012, `Microsoft http://microsoft.com`_ .. [PSCI] `Power State Coordination Interface Issue D (PSCI v1.1) http://infocenter.arm.com/help//topic/com.arm.doc.den0022d/Power_State_Coordination_Interface_PDD_v1_1_DEN0022D.pdf`_, 21 April 2017, `Arm Limited http://arm.com`_