On 18/05/2018 20:49, Dong Wei wrote:
Yes, I am referring to the upcoming SBBR v1.1 content. We changed the reference
to PSCI back to 1.0 because that version is what we need for the MP support,
1.1 is also fine but not the minimal requirement.
Ah, that makes sense. I'll take a look next week and rework the EBBR
text to match.
g.
- DW
-
-----Original Message-----
From: Grant Likely
Sent: Friday, May 18, 2018 12:47 PM
To: Dong Wei <[email protected]>
Cc: [email protected]; nd <[email protected]>; arm.ebbr-discuss
<[email protected]>
Subject: Re: [Arm.ebbr-discuss] [PATCH] Add chapter for privileged/secure
firmware
Hi Dong,
Thanks for the comments. Replies below...
On 18/05/2018 19:01, Dong Wei wrote:
This part has been changed in the SBBR spec as we do expect server SoC to
support EL3 so we removed the non-PSCI mechanism. Also the PSCI Spec reference
is 1.0:
Can you double check that please? The copy on developer.arm.com is issue C
(psci 1.0), but there is a more recent copy on infocenter; issue D for PSCI 1.1.
UEFI is defined as a uniprocessor specification that only uses a single CPU
core for booting.
Platforms providing EL3 must implement the Power State Coordination Interface
(PSCI) [5]. This interface will be as the main method to boot secondary cores,
implementing CPU idling, and providing reset and shutdown runtime services.
... some ACPI related requirements...
All secondary cores remain powered down during boot. After boot, OSPM can call
CPU_ON() into the PSCI firmware to power up a chosen core. The PSCI firmware
powers up, initializes the core, and starts execution at the provided address.
That helps. Perhaps I'll drop the MP Boot language entirely and leave it at
PSCI as the preferred, but Linux spin tables as a fallback, and only for DT
systems.
g.
- DW
-
-----Original Message-----
From: [email protected]
<[email protected]> On Behalf Of Grant Likely
Sent: Friday, May 18, 2018 6:06 AM
Cc: [email protected]; nd <[email protected]>;
arm.ebbr-discuss <[email protected]>
Subject: [Arm.ebbr-discuss] [PATCH] Add chapter for privileged/secure
firmware
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 <[email protected]>
---
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>`_
--
2.13.0
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