Closes: #52
The no-map property of the /reserved-memory device tree nodes is used to signal that a memory region shall not be accessed by the operating system, even not via speculative access.
/reserved-memory nodes without the no-map property describe memory that have special usage by the operating system.
This difference has to be reflected in the memory map returned by GetMemoryMap().
Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- source/chapter2-uefi.rst | 13 +++++++++++++ source/references.rst | 4 ++++ 2 files changed, 17 insertions(+)
diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst index 74ef70e..f410c57 100644 --- a/source/chapter2-uefi.rst +++ b/source/chapter2-uefi.rst @@ -74,6 +74,19 @@ that virtual addresses must equal physical addresses.
The default RAM allocated attribute must be EFI_MEMORY_WB.
+In the device tree reserved memory in modelled as a /reserved-memory nodes +[RESMEM]_. The reserved-memory node MAY carry either the no-map or the resue +property. It MUST NOT carry both properties as this would be contradictary. + +A 'no-map' reserved memory node describes memory that the UEFI payload MUST NOT +access. It MUST be modelled as a EfiReservedMemoryType entry in the memory map. + +A reserved memory without the 'no-map' describes memory that MAY be used by the +UEFI payload after ExitBootServices(). It MUST be modelled as a memory map entry +that can only be used by the UEFI payload after ExitBootServices(). It +is recommended to use EfiBootServicesData. The node MUST NOT be modelled as +EfiReservedMemoryType and NOT as EfiConventionalMemory. + Configuration Tables --------------------
diff --git a/source/references.rst b/source/references.rst index 1eb0509..2434137 100644 --- a/source/references.rst +++ b/source/references.rst @@ -16,6 +16,10 @@ https://static.docs.arm.com/den0022/c/DEN0022C_Power_State_Coordination_Interface.pdf`_ 30 January 2015, `Arm Limited http://arm.com`_
+.. [RESMEM] `Reserved memory regions + https://www.kernel.org/doc/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt`_, + 21 July 2020, Linux kernel + .. [SBBR] `Arm Server Base Boot Requirements specification Issue B (v1.0) https://static.docs.arm.com/den0044/b/DEN0044B_Server_Base_Boot_Requirements.pdf`_ 8 March 2016, `Arm Limited http://arm.com`_ -- 2.28.0