On Tue, 5 May 2020 at 13:49, Grant Likely grant.likely@arm.com wrote:

UEFI 2.8 Errata A changed RuntimeServiceSupported value to be passed via an EFI_RT_PROPERTIES_TABLE instead of via a runtime variable.

This is a breaking change and we should do a new EBBR release in short order to keep EBBR up to date with what is in UEFI. Unsure what the overall impact will be. U-Boot implements the variable method which will need to be changed to a table. It is unclear if any OSes depend heavily on it being implemented.

U-Boot has already been updated. Linux never implemented the old method, and support for the new method will be part of the v5.7 release. No other OSes implement it at all today afaik.

Cc: Andrei Warkentin awarkentin@vmware.com Cc: Francois Ozog francois.ozog@linaro.org Cc: Ard Biesheuvel ardb@kernel.org Signed-off-by: Grant Likely grant.likely@arm.com

---

source/chapter2-uefi.rst | 7 ++++--- source/references.rst | 6 +++--- 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst index fe03ae3..b622abe 100644 --- a/source/chapter2-uefi.rst +++ b/source/chapter2-uefi.rst @@ -9,7 +9,7 @@ platforms.

UEFI Version

-This document uses version 2.8 of the UEFI specification [UEFI]_. +This document uses version 2.8 Errata A of the UEFI specification [UEFI]_.

UEFI Compliance

@@ -111,7 +111,7 @@ during both boot services and runtime services. However, it isn't always practical for all EFI_RUNTIME_SERVICES functions to be callable during runtime services due to hardware limitations. If any EFI_RUNTIME_SERVICES functions are only available during boot services -then firmware shall provide the global `RuntimeServicesSupported` variable to +then firmware shall provide the `EFI_RT_PROPERTIES_TABLE` to indicate which functions are available during runtime services. Functions that are not available during runtime services shall return EFI_UNSUPPORTED. @@ -202,7 +202,8 @@ If a platform does not implement modifying non-volatile variables with SetVariable() after ExitBootServices(), then firmware shall return EFI_UNSUPPORTED for any call to SetVariable(), and must advertise that SetVariable() isn't available during runtime services -via the `RuntimeServicesSupported` variable as defined in [UEFI]_ § 8.1. +via the `RuntimeServicesSupported` value in the `EFI_RT_PROPERTIES_TABLE` +as defined in [UEFI]_ § 4.6. EFI applications can read `RuntimeServicesSupported` to determine if calls to SetVariable() need to be performed before calling ExitBootServices().

diff --git a/source/references.rst b/source/references.rst index d901bb1..1eb0509 100644 --- a/source/references.rst +++ b/source/references.rst @@ -20,6 +20,6 @@ https://static.docs.arm.com/den0044/b/DEN0044B_Server_Base_Boot_Requirements.pdf`_ 8 March 2016, `Arm Limited http://arm.com`_

-.. [UEFI] `Unified Extensable Firmware Interface Specification v2.8

• http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf`_,
• March 2019, `UEFI Forum http://www.uefi.org`_

+.. [UEFI] `Unified Extensable Firmware Interface Specification v2.8 Errata A

'extensible'

• https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf`_,
• February 2020, `UEFI Forum http://www.uefi.org`_

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