Documentation: arm: Update for DT-only platforms

The documentation specified that a machine type is mandatory and made
that assumption in a few places.  However, for DT-only platforms, the
current advice is that no machine type should be registered, so update
accordingly.

Signed-off-by: Gregory Fong <gregory.0xf0@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting
index 371814a36719..83c1df2fc758 100644
--- a/Documentation/arm/Booting
+++ b/Documentation/arm/Booting
@@ -58,13 +58,18 @@ serial format options as described in
 --------------------------
 
 Existing boot loaders:          OPTIONAL
-New boot loaders:               MANDATORY
+New boot loaders:               MANDATORY except for DT-only platforms
 
 The boot loader should detect the machine type its running on by some
 method.  Whether this is a hard coded value or some algorithm that
 looks at the connected hardware is beyond the scope of this document.
 The boot loader must ultimately be able to provide a MACH_TYPE_xxx
-value to the kernel. (see linux/arch/arm/tools/mach-types).
+value to the kernel. (see linux/arch/arm/tools/mach-types).  This
+should be passed to the kernel in register r1.
+
+For DT-only platforms, the machine type will be determined by device
+tree.  set the machine type to all ones (~0).  This is not strictly
+necessary, but assures that it will not match any existing types.
 
 4. Setup boot data
 ------------------