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Recommend usage of partition type GUIDs to find firmware
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If the firmware is loaded from a GPT partitioned medium, it should use
the partition type GUID (and not sector number or partition number) to
identify the relevant partition. This GUID should be unique for each
board type.

Signed-off-by: Heinrich Schuchardt <[email protected]>
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xypron committed May 5, 2023
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Expand Up @@ -117,6 +117,13 @@ non-protective partitions).
There are no requirements on the contents or layout of the firmware
protective partition.

Devices should use the partition type GUID to identify the partition with
the firmware to load. This is preferable over fixed sector or partition
numbers as it imposes the least restrictions on the partitioning scheme.

Firmware partition type GUIDs should be unique for a board type. This
allows creating media that can be booted on a multitude of boards.

Placing GPT data structures away from firmware images can be accomplished by
adjusting the GUID Partition Entry array location
(adjusting the values of `PartitionEntryLBA` and `NumberOfPartitionEntries`,
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