Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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 000000000..965a37407
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+++ b/Documentation/x86/booting-dt.rst
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+.. 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.