[PATCH v5 1/6] docs/arm: Document Xen booting protocol on Armv8-R

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Document the requirement needed to boot Xen on Armv8-R platforms.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Reviewed-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
---
v5 changes:
 - restructured and removed some EL3 reference that might not
   be there on Armv8-R aarch64
 - add R-by Ayan and Michal
v4 changes:
 - New patch
---
 docs/misc/arm/booting.txt | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/docs/misc/arm/booting.txt b/docs/misc/arm/booting.txt
index 21ae74837dcc..ca05274392be 100644
--- a/docs/misc/arm/booting.txt
+++ b/docs/misc/arm/booting.txt
@@ -56,12 +56,17 @@ image header to determine the load address, entry point, 
etc.
 Firmware/bootloader requirements
 --------------------------------
 
-Xen relies on some settings the firmware has to configure in EL3 before 
starting Xen.
+Xen relies on some settings the firmware has to configure before starting Xen.
 
-* Xen must be entered in NS EL2 mode
+* Xen must be entered in:
+  * Non-Secure EL2 mode for Armv8-A Arm64 and Arm32, Armv8-R Arm32.
+  * Secure EL2 mode for Armv8-R Arm64.
 
-* The bit SCR_EL3.HCE (resp. SCR.HCE for 32-bit ARM) must be set to 1.
+* When EL3 is supported, the bit SCR_EL3.HCE (resp. SCR.HCE for 32-bit ARM) 
must
+  be set to 1.
 
+* Xen must be entered with MMU/MPU off and data cache disabled (SCTLR_EL2.M bit
+  and SCTLR_EL2.C set to 0).
 
 [1] linux/Documentation/arm/booting.rst
 Latest version: 
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/arch/arm/booting.rst
-- 
2.34.1