[XEN][PATCH v11 05/20] xen/arm: Add CONFIG_OVERLAY_DTB

[Vikram Garhwal <vikram.garhwal@xxxxxxx>]

Introduce a config option where the user can enable support for adding/removing
device tree nodes using a device tree binary overlay.

Update SUPPORT.md and CHANGELOG.md to state the Device Tree Overlays support for
Arm.

Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>
Acked-by: Henry Wang <Henry.Wang@xxxxxxx>
Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>

---
Changes from v9:
    Fix style.
Changes from v7:
    Add this feature as "experimental support" in CHANGELOG.md
---
---
 CHANGELOG.md         | 2 ++
 SUPPORT.md           | 6 ++++++
 xen/arch/arm/Kconfig | 5 +++++
 3 files changed, 13 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2516526589..24636b8eaf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,8 @@ The format is based on [Keep a 
Changelog](https://keepachangelog.com/en/1.0.0/)
  - On Arm, add suport for Firmware Framework for Arm A-profile (FF-A) Mediator
    (Tech Preview)
  - Add Intel Hardware P-States (HWP) cpufreq driver.
+ - On Arm, experimental support for dynamic addition/removal of Xen device tree
+   nodes using a device tree overlay binary (.dtbo).
 
 ### Removed
  - On x86, the "pku" command line option has been removed.  It has never
diff --git a/SUPPORT.md b/SUPPORT.md
index 6ce0ec29b0..3461f5cf2f 100644
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -855,6 +855,12 @@ xen/arch/arm/tee/ffa.c for limitations.
 
     Status: Supported
 
+### Device Tree Overlays
+
+Add/Remove device tree nodes using a device tree overlay binary (.dtbo).
+
+    Status, ARM: Experimental
+
 ### ARM: Guest ACPI support
 
     Status: Supported
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 57bd1d01d7..650aca99ac 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -92,6 +92,11 @@ config HAS_ITS
         bool "GICv3 ITS MSI controller support (UNSUPPORTED)" if UNSUPPORTED
         depends on GICV3 && !NEW_VGIC && !ARM_32
 
+config OVERLAY_DTB
+       bool "DTB overlay support (UNSUPPORTED)" if UNSUPPORTED
+       help
+         Dynamic addition/removal of Xen device tree nodes using a dtbo.
+
 config HVM
         def_bool y
 
-- 
2.17.1