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1.. SPDX-License-Identifier: GPL-2.02 3DeviceTree Booting4------------------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 32bit8 entry point once it switched into protected mode). That entry point9 supports one calling convention which is documented in10 Documentation/arch/x86/boot.rst11 The physical pointer to the device-tree block is passed via setup_data12 which requires at least boot protocol 2.09.13 The type filed is defined as14 15 #define SETUP_DTB 216 17 This device-tree is used as an extension to the "boot page". As such it18 does not parse / consider data which is already covered by the boot19 page. This includes memory size, reserved ranges, command line arguments20 or initrd address. It simply holds information which can not be retrieved21 otherwise like interrupt routing or a list of devices behind an I2C bus.22