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Diffstat (limited to 'Documentation/x86/booting-dt.rst')
| -rw-r--r-- | Documentation/x86/booting-dt.rst | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/x86/booting-dt.rst b/Documentation/x86/booting-dt.rst new file mode 100644 index 000000000000..965a374071ab --- /dev/null +++ b/Documentation/x86/booting-dt.rst @@ -0,0 +1,21 @@ +.. SPDX-License-Identifier: GPL-2.0 + +DeviceTree Booting +------------------ + + There is one single 32bit entry point to the kernel at code32_start, + the decompressor (the real mode entry point goes to the same 32bit + entry point once it switched into protected mode). That entry point + supports one calling convention which is documented in + Documentation/x86/boot.rst + The physical pointer to the device-tree block is passed via setup_data + which requires at least boot protocol 2.09. + The type filed is defined as + + #define SETUP_DTB 2 + + This device-tree is used as an extension to the "boot page". As such it + does not parse / consider data which is already covered by the boot + page. This includes memory size, reserved ranges, command line arguments + or initrd address. It simply holds information which can not be retrieved + otherwise like interrupt routing or a list of devices behind an I2C bus. |