The new uImage format allows more flexibility in handling images of various types (kernel, ramdisk, etc.), it also enhances integrity protection of images with sha1 and md5 checksums.
This page hosts a formal specification of U-Boot Image wrapper using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
digraph {
rankdir=LR;
node [shape=plaintext];
subgraph cluster__uimage {
label="Uimage";
graph[style=dotted];
uimage__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="header_pos">0</TD><TD PORT="header_size">64</TD><TD>Uheader</TD><TD PORT="header_type">header</TD></TR>
<TR><TD PORT="data_pos">64</TD><TD PORT="data_size">header.len_image</TD><TD></TD><TD PORT="data_type">data</TD></TR>
</TABLE>>];
subgraph cluster__uheader {
label="Uimage::Uheader";
graph[style=dotted];
uheader__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="magic_pos">0</TD><TD PORT="magic_size">4</TD><TD></TD><TD PORT="magic_type">magic</TD></TR>
<TR><TD PORT="header_crc_pos">4</TD><TD PORT="header_crc_size">4</TD><TD>u4be</TD><TD PORT="header_crc_type">header_crc</TD></TR>
<TR><TD PORT="timestamp_pos">8</TD><TD PORT="timestamp_size">4</TD><TD>u4be</TD><TD PORT="timestamp_type">timestamp</TD></TR>
<TR><TD PORT="len_image_pos">12</TD><TD PORT="len_image_size">4</TD><TD>u4be</TD><TD PORT="len_image_type">len_image</TD></TR>
<TR><TD PORT="load_address_pos">16</TD><TD PORT="load_address_size">4</TD><TD>u4be</TD><TD PORT="load_address_type">load_address</TD></TR>
<TR><TD PORT="entry_address_pos">20</TD><TD PORT="entry_address_size">4</TD><TD>u4be</TD><TD PORT="entry_address_type">entry_address</TD></TR>
<TR><TD PORT="data_crc_pos">24</TD><TD PORT="data_crc_size">4</TD><TD>u4be</TD><TD PORT="data_crc_type">data_crc</TD></TR>
<TR><TD PORT="os_type_pos">28</TD><TD PORT="os_type_size">1</TD><TD>u1→UimageOs</TD><TD PORT="os_type_type">os_type</TD></TR>
<TR><TD PORT="architecture_pos">29</TD><TD PORT="architecture_size">1</TD><TD>u1→UimageArch</TD><TD PORT="architecture_type">architecture</TD></TR>
<TR><TD PORT="image_type_pos">30</TD><TD PORT="image_type_size">1</TD><TD>u1→UimageType</TD><TD PORT="image_type_type">image_type</TD></TR>
<TR><TD PORT="compression_type_pos">31</TD><TD PORT="compression_type_size">1</TD><TD>u1→UimageComp</TD><TD PORT="compression_type_type">compression_type</TD></TR>
<TR><TD PORT="name_pos">32</TD><TD PORT="name_size">32</TD><TD>str(UTF-8)</TD><TD PORT="name_type">name</TD></TR>
</TABLE>>];
}
}
uimage__seq:header_type -> uheader__seq [style=bold];
uheader__seq:len_image_type -> uimage__seq:data_size [color="#404040"];
}