feat(device): impl utilities to assist in managing device path.#5
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feat(device): impl utilities to assist in managing device path.#5
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Changes in this PR:
get_device_path_size(),duplicate_device_path(),append_device_path(),append_device_node(),append_device_path_instance(),get_next_device_path_instance(),is_device_path_multi_instance()andcreate_device_node()functions of DevicePathUtilities.Note:
The UEFI Device Path is essentially a sequence of “nodes” (Device Path Nodes) arranged one after another. Each node starts with a fixed 4-byte header:
Type (1B) | SubType (1B) | Length (2B, little-endian). The Length field specifies the total size of the node, including the header and its payload, which varies depending on the node type. The entire path always ends with a terminator node:Type=0x7F (End), SubType=0xFF (End Entire), Length=4.For multi-instance paths, different instances are separated by an End Instance node
(Type=0x7F, SubType=0x01, Length=4), and the whole path is still terminated by a final End Entire. Conceptually, the structure looks like:[Node1][Node2]...[End Instance?]...[End Entire]Together, the ordered nodes describe the exact location and access method for a device within the system.