xen/doc: Improve Dom0-less documentation

- Changed unprintable characters with %s/\%xA0/ /g
  So all the spaces are 0x20 now.

- Added address-cells and size-cells to configuration example.
  This resolves the dom0less boot issue in case of arm64.

- Added some notes about xl tools usage in case of dom0less.

Signed-off-by: Viktor Mitin <viktor_mitin@epam.com>
[julien: Remove newline at the end of the file]
Acked-by: Julien Grall <julien.grall@arm.com>

docs/features/dom0less.pandoc

@@ -40,8 +40,8 @@ to boot. For example if this is the bootcmd for Xen and Dom0:
 
     bootm 0x1400000 0x9000000 0x1280000
 
-If we want to add one DomU with Image-DomU as the DomU kernel
-and ramdisk-DomU as DomU ramdisk:
+If we want to add one DomU with Image-DomU as the DomU kernel
+and ramdisk-DomU as DomU ramdisk:
 
     tftpb 0x1280000 xen.dtb
     tftpb 0x80000 xen-Image
@@ -61,27 +61,32 @@ the presence of the additional VM and its configuration. It is done via
 device tree adding a node under /chosen as follows:
 
     domU1 {
-        compatible = "xen,domain";
-        memory = <0x20000>;
-        cpus = 1;
-        vpl011;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        compatible = "xen,domain";
+        memory = <0 0x20000>;
+        cpus = <1>;
+        vpl011;
 
-        module@2000000 {
-            compatible = "multiboot,kernel", "multiboot,module";
-            reg = <0x2000000 0xffffff>;
-            bootargs = "console=ttyAMA0";
-        };
+        module@2000000 {
+            compatible = "multiboot,kernel", "multiboot,module";
+            reg = <0x2000000 0xffffff>;
+            bootargs = "console=ttyAMA0";
+        };
 
-        module@30000000 {
-            compatible = "multiboot,ramdisk", "multiboot,module";
-            reg = <0x3000000 0xffffff>;
-        };
+        module@30000000 {
+            compatible = "multiboot,ramdisk", "multiboot,module";
+            reg = <0x3000000 0xffffff>;
+        };
     };
 
-Where memory is the memory of the VM in KBs, cpus is the number of
-cpus. module@2000000 and module@3000000 advertise where the kernel and
+Where memory is the memory of the VM in KBs, cpus is the number of
+cpus. module@2000000 and module@3000000 advertise where the kernel and
 ramdisk are in memory.
 
+Note: the size specified should exactly match the size of the Kernel/initramfs.
+Otherwise, they may be unusable in Xen (for instance if they are compressed).
+
 See docs/misc/arm/device-tree/booting.txt for more information.
 
 Limitations
@@ -111,3 +116,20 @@ limitations:
   the Xen command line. The NULL scheduler automatically assigns and
   pins vCPUs to pCPUs, but the vCPU-pCPU assignments cannot be
   configured.
+
+Notes
+-----
+
+- 'xl console' command will not attach to the domain's console in case
+  of dom0less. DomU are domains created by Xen (similar to Dom0) and
+  therefore they are all managed by Xen and some of the commands may not work.
+
+  A user is allowed to configure the key sequence to switch input.
+  Pressing the Xen "conswitch" (Ctrl-A by default) three times
+  switches input in case of dom0less mode.
+
+- Domains created by Xen will have no name at boot. Domain-0 has a name
+  thanks to the helper xen-init-dom0 called at boot by the initscript.
+  If you want to setup DomU name, then you will have to create the xenstore
+  node associated. By default DomU names are shown as '(null)' in the
+  xl domains list.