1.. SPDX-License-Identifier: GPL-2.0
2
3DeviceTree Booting
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5
6  There is one single 32bit entry point to the kernel at code32_start,
7  the decompressor (the real mode entry point goes to the same  32bit
8  entry point once it switched into protected mode). That entry point
9  supports one calling convention which is documented in
10  Documentation/x86/boot.rst
11  The physical pointer to the device-tree block is passed via setup_data
12  which requires at least boot protocol 2.09.
13  The type filed is defined as
14
15  #define SETUP_DTB                      2
16
17  This device-tree is used as an extension to the "boot page". As such it
18  does not parse / consider data which is already covered by the boot
19  page. This includes memory size, reserved ranges, command line arguments
20  or initrd address. It simply holds information which can not be retrieved
21  otherwise like interrupt routing or a list of devices behind an I2C bus.
22