[Xen-devel] [PATCH v3 09/10] xen: arm: update multiboot device tree bindings.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v2: (Try to) Clarify some wording, add examples to help.
---
 docs/misc/arm/device-tree/booting.txt |   54 +++++++++++++++++++++++++++++----
 1 file changed, 48 insertions(+), 6 deletions(-)

diff --git a/docs/misc/arm/device-tree/booting.txt 
b/docs/misc/arm/device-tree/booting.txt
index bfb8d01..d967061 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -8,15 +8,31 @@ Each node contains the following properties:
 
 - compatible
 
-       Must be:
+       Must always include at least the generic compatiblity string:
 
-               "xen,<type>", "xen,multiboot-module"
+               "multiboot,module"
 
-       where <type> must be one of:
+       Optionally a more specific compatible string may be used in
+       addition to the above. One of:
 
-       - "linux-zimage" -- the dom0 kernel
-       - "linux-initrd" -- the dom0 ramdisk
-       - "xsm-policy"   -- XSM policy blob
+       - "multiboot,kernel"    -- the dom0 kernel
+       - "multiboot,ramdisk"   -- the dom0 ramdisk
+       - "xen,xsm-policy"      -- XSM policy blob
+
+       It is normally recommended to include a more specific
+       compatible string (if one applies) in addition to the generic
+       string (which must always be present).
+
+        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.
+
+       - "xen,multiboot-module" equivalent to "multiboot,module"
+       - "xen,linux-zimage"     equivalent to "multiboot,kernel"
+       - "xen,linux-initrd"     equivalent to "multiboot,ramdisk"
+
+       For compatibility with Xen 4.4 the more specific "xen,linux-*"
+       names are non-optional and must be included.
 
 - reg
 
@@ -29,6 +45,32 @@ Each node contains the following properties:
        priority of this field vs. other mechanisms of specifying the
        bootargs for the kernel.
 
+Examples
+========
+
+A boot module of unspecified type:
+
+       module@0xc0000000 {
+               compatible = "multiboot,module";
+               reg = <0xc0000000 0x1234>;
+               bootargs = "...";
+       };
+
+A boot module containing a ramdisk:
+
+       module@0xd0000000 {
+               compatible = "multiboot,ramdisk", "multiboot,module";
+               reg = <0xd0000000 0x5678>;
+       };
+
+The previous examples are compatible with Xen 4.5+ only.
+
+To be compatible with Xen 4.4 as well use the legacy names:
+
+       module@0xd0000000 {
+               compatible = "xen,linux-initrd", "xen,multiboot-module";
+               reg = <0xd0000000 0x5678>;
+       };
 
 Command lines
 =============
-- 
1.7.10.4


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