infra/common: document WinPE boot

Add a new document that explains the procedure to boot WinPE on the SGI/RD
platforms.

Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>
Change-Id: Ic0a0a03a660fece2f38a1cb38f6b6da932c353e6

docs/infra/common/winpe-boot.rst

+How to boot WinPE
+=================
+
+.. contents::
+
+
+WinPE boot support
+------------------
+RD software stack supports the boot of Windows Preinstallation Environment
+(WinPE). A pre-built WinPE disk image is provided as a SATA disk to the FVP
+which then is used to boot WinPE.
+
+
+Platform Names
+--------------
+
+Arm's Infra reference platforms are assigned names in order to allow the build
+and execute scripts to recognize the platform that has to be buit and executed.
+The names for the reference platforms are listed below. Please make a note
+of the name of the platform of your choice. This name is required to start the
+build and execute procedure. The names under 'Platform Name' column has to be
+used in place of the placeholder ``<platform>`` as mentioned in the commands
+listed below.
+
++--------------------------+-------------------------+
+| Reference Platform       | Platform Name           |
++==========================+=========================+
+| SGI-575                  | sgi575                  |
++--------------------------+-------------------------+
+| RD-N1-Edge (Single Chip) | rdn1edge                |
++--------------------------+-------------------------+
+| RD-N1-Edge (Dual Chip)   | rdn1edgex2              |
++--------------------------+-------------------------+
+| RD-E1-Edge               | rde1edge                |
++--------------------------+-------------------------+
+| RD-Daniel Config-M       | rddaniel                |
++--------------------------+-------------------------+
+| RD-Daniel Config-XLR     | rddanielxlr             |
++--------------------------+-------------------------+
+| RD-N2                    | rdn2                    |
++--------------------------+-------------------------+
+
+
+Sync the required platform software
+-----------------------------------
+
+To obtain the required sources for the platform, follow the steps listed on the
+`Obtaining the platform software`_ page. Ensure that the
+platform software is downloaded before proceeding with the steps listed below.
+Also, note the host machine requirements listed on that page which is essential
+to build and execute the platform software stack.
+
+
+Procedure to build SGI/RD software stack for WinPE boot
+-------------------------------------------------------
+
+The SGI/RD platform software stack has to be first built to prepare for the
+WinPE boot. The procedure to build the RD-Daniel platform stack is listed below.
+
+To build the SGI/RD software stack, the command to be used is
+
+::
+
+  ./build-scripts/build-test-uefi.sh -p <platform> <command>
+
+Supported command line options are listed below
+
+* <platform>
+
+  - Supported platforms are listed in `Platform Names`_.
+
+* <command>
+
+  - ``clean``
+  - ``build``
+  - ``package``
+  - ``all`` (all of the three above)
+
+
+Examples of the build command are
+
+
+- Command to clean, build and package the RD-N2 software stack needed for the
+  WinPE boot on the RD-N2 platform:
+
+  ::
+
+    ./build-scripts/build-test-uefi.sh -p rdn2 all
+
+- Command to remove the generated outputs (binaries) of the software stack for
+  the RD-N2 platform:
+
+  ::
+
+    ./build-scripts/build-test-uefi.sh -p rdn2 clean
+
+- Command to perform an incremental build of the software components included in
+  the software stack for the RD-Daniel Config-M platform:
+
+  *Note:* this command should be followed by the ``package`` command to
+  complete the preparation of the fip image.
+
+  ::
+
+    ./build-scripts/build-test-uefi.sh -p rddaniel build
+
+- Command to package the previously built software stack and prepares the fip
+  image:
+
+  ::
+
+    ./build-scripts/build-test-uefi.sh -p rddaniel package
+
+
+Procedure for preparing a WinPE disk image
+------------------------------------------
+
+To prepare a WinPE disk image, follow the instructions listed on this page:
+`Boot to WinPE
+<https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/boot-to-winpe>`_
+
+In addition to the above, to allow the text console to be used as the boot
+message console, mount the WinPE disk image. Note: The instructions to
+mount the WinPE image is outside of the scope of this document. Use the following
+commands to enable the use of text console for boot messages.
+
+  ::
+
+    cd <mount-path>\media\EFI\Microsoft\Boot
+    bcdedit /store BCD /set {default} EMS ON
+
+Continue to unmount the WinPE image and package it (instructions for these are
+outside of the scope of this document).
+
+
+Procedure for booting WinPE on SGI/RD platform
+----------------------------------------------
+
+To boot from the WinPE disk image, use the following command:
+
+- Set ``MODEL`` path before launching the model:
+
+  ::
+
+    export MODEL=<absolute path to the platform FVP binary>
+
+- If platform is SGI-575:
+
+  ::
+
+    cd model-scripts/sgi
+
+- If platform is an RD:
+
+  ::
+
+    cd model-scripts/rdinfra
+
+- Begin WinPE boot:
+
+  ::
+
+    ./distro.sh -p <platform> -d <satadisk_path> -a <additional_params> -n [true|false]
+
+Supported command line options are listed below
+
+*  -p <platform>
+
+   - Supported platforms are listed in `Platform Names`_.
+
+*  -d <satadisk_path>
+
+   -  Absolute path to the WinPE disk image created using the previous section.
+
+*  -n [true|false] (optional)
+
+   -  Controls the use of network ports by the model. If network ports have
+      to be enabled, use 'true' as the option. Default value is set to
+      'false'.
+
+*  -a <additional_params>
+
+   -  Specify any additional model parameters to be passed. The model
+      parameters and the data to be passed to those parameters can be found
+      in the FVP documentation.
+
+
+Example command  functionality are as listed below.
+
+- Command to begin the WinPE boot on the RD-Daniel platform using the ``WinPE_arm64.iso``
+  disk image. Follow the instructions on console to complete the WinPE boot.
+
+  ::
+
+    ./distro.sh -p rddaniel -d /absolute/path/to/WinPE_arm64.iso
+
+
+--------------
+
+*Copyright (c) 2020, Arm Limited. All rights reserved.*
+
+
+.. _Obtaining the platform software:
+   docs/infra/common/obtain-platform-software-stack.rst