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diff --git a/Documentation/user/booting-linux.rst b/Documentation/user/booting-linux.rst
index 98628faf9d..f26299efd9 100644
--- a/Documentation/user/booting-linux.rst
+++ b/Documentation/user/booting-linux.rst
@@ -99,6 +99,20 @@ with addpart to the Kernel:
Kernel command line: mtdparts=physmap-flash.0:512k(bootloader),512k(env),4M(kernel),-(root);
mxc_nand:1M(bootloader),1M(env),4M(kernel),-(root)
+Creating root= options for the Kernel
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+It's a common case that the Linux Kernel is loaded from a filesystem
+that later becomes the root filesystem for the Kernel. For several
+filesystems barebox can automatically append a suitable root= option
+to the Kernel command line. This is done when ``global.bootm.appendroot``
+is true. How the root= option is appended depends on the device type
+and filesystem the kernel is booted from. For disk like devices (SD/MMC,
+ATA) the partition UUID will be used, the root= option will be something
+like ``root=PARTUUID=deadbeef-1``. For UBIFS fileystems it will be
+``root=ubi0:volname ubi.mtd=mtdpartname rootfstype=ubifs``. NFS
+filesystems will result in ``root=/dev/nfs nfsroot=ip:/path/to/nfsroot,v3,tcp``.
+The ``v3,tcp`` part is configurable in ``global.linux.rootnfsopts``.
The boot command
----------------