[PATCH v2] arm/docs: Clarify legacy DT bindings on UEFI

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Since the introduction of UEFI boot for Xen, the legacy
compatible strings were not supported and the stub code
was checking only the presence of “multiboot,module” to
require the Xen UEFI configuration file or not.
The documentation was not updated to specify that behavior.

Add a phrase to docs/misc/arm/device-tree/booting.txt
to clarify it.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
Changes in v2:
- dropped redundant wording in docs/misc/arm/device-tree/booting.txt
- Add more details to the commit message
---
 docs/misc/arm/device-tree/booting.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/misc/arm/device-tree/booting.txt 
b/docs/misc/arm/device-tree/booting.txt
index c6a775f4e8..71895663a4 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -51,6 +51,8 @@ Each node contains the following properties:
        Xen 4.4 supported a different set of legacy compatible strings
        which remain supported such that systems supporting both 4.4
        and later can use a single DTB.
+       However when booting Xen using UEFI, the legacy compatible
+       strings are not supported.
 
        - "xen,multiboot-module" equivalent to "multiboot,module"
        - "xen,linux-zimage"     equivalent to "multiboot,kernel"
-- 
2.17.1