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. However, real world impact is minimal. U-Boot has already converted to the new method, and Linux only ever implemented the EFI_RT_PROPERTIES_TABLE method.
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 82b1a42..c42691b 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 + https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf`_, + February 2020, `UEFI Forum http://www.uefi.org`_
Describe details of how to pass a DTB from firmware to the OS. Specifies the GUID for passing the DTB via the EFI_SYSTEM_TABLE and the memory type needs to be EfiACPIReclaimMemory. Also specifies that the DTB must be handed off and no longer modified by firmware once execution of EFI application and drivers begins.
Fixes: #45 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 | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-)
diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst index c42691b..c9c0101 100644 --- a/source/chapter2-uefi.rst +++ b/source/chapter2-uefi.rst @@ -86,12 +86,41 @@ tables. - An Advanced Configuration and Power Interface [ACPI]_ table, or - a Devicetree [DTSPEC]_ system description
-As stated above, EBBR systems must not provide both ACPI and Devicetree +EBBR systems must not provide both ACPI and Devicetree tables at the same time. Systems that support both interfaces must provide a configuration mechanism to select either ACPI or Devicetree, and must ensure only the selected interface is provided to the OS loader.
+Devicetree +^^^^^^^^^^ + +If firmware provides a Devicetree system description then it must be provided +in Flattened Devicetree (DTB) format version 17 or higher as described in +[DTSPEC]_ § 5.1. +The following GUID must be used in the EFI system table ([UEFI]_ § 4) +to identify the DTB. +The DTB must be contained in memory of type EfiACPIReclaimMemory. + +.. code-block:: c + + #define EFI_DTB_GUID \ + EFI_GUID(0xb1b621d5, 0xf19c, 0x41a5, \ + 0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0) + +Firmware must have the DTB resident in memory and installed in the EFI system table +before executing any UEFI applications or drivers that are not part of the system +firmware image. +Once the DTB is installed as a configuration table, +the system firmware must not make any modification to it or reference any data +contained within the DTB. + +UEFI applications are permitted to modify or replace the loaded DTB. +System firmware must not depend on any data contained within the DTB. +If system firmware makes use of a DTB for its own configuration, +it should use a separate private copy that is not installed in the +EFI System Table or otherwise be exposed to EFI applications. + UEFI Secure Boot (Optional) ---------------------------
Hi everyone,
Discussion on these changes seems to have settled down. If I don't hear any strong objections in the next day I'm going to commit them to the main repo.
g.
---
source/chapter2-uefi.rst | 38 ++++++++++++++++++++++++++++++++++---- source/references.rst | 6 +++--- 2 files changed, 37 insertions(+), 7 deletions(-)
boot-architecture@lists.linaro.org
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Grant Likely