Getting Started Guide: update (and simplify) GSG

Update the Getting Started Guide to remove some instructions that
are now obsolete and add details of the cmdline parameters that
can be passed to the ACRN hypervisor (EFI), namely:
* bootloader=
* uart=

The wording of the GSG has been made less specific to the NUC
platform so we can refer to it for new platform being supported
without causing confusion to the reader

Signed-off-by: Geoffroy Van Cutsem <geoffroy.vancutsem@intel.com>

Author: Geoffroy Van Cutsem

doc/getting_started/index.rst

@@ -15,8 +15,11 @@ Hardware setup
 **************
 
 The Intel |reg| NUC (NUC6CAYH) is the supported reference target
-platform for ACRN work, as described in :ref:`hardware`, and is the only
-platform currently tested with these setup instructions.
+platform for ACRN work, as described in :ref:`hardware`, and is the main
+platform currently tested with these setup instructions. The
+`UP Squared board <http://www.up-board.org/upsquared/>`_ (UP2) is also
+known to work and the few specificities for it are described
+in :ref:`getting_started_up2`.
 
 The recommended NUC hardware configuration is:
 
@@ -26,9 +29,6 @@ The recommended NUC hardware configuration is:
 - Memory: 8G DDR3
 - SSD: 120G SATA
 
-Software setup
-**************
-
 Firmware update on the NUC
 ==========================
 
@@ -37,12 +37,15 @@ Follow these `BIOS Update Instructions
 <https://www.intel.com/content/www/us/en/support/articles/000005636.html>`__
 for downloading and flashing an updated BIOS for the NUC.
 
+Software setup
+**************
+
 Set up a Clear Linux Operating System
 =====================================
 
 Currently, an installable version of ARCN does not exist. Therefore, you
-need to setup a base Clear Linux OS to bootstrap ACRN on the NUC. You'll
-need a network connection for your NUC to complete this setup.
+need to setup a base Clear Linux OS to bootstrap ACRN on your platform. You'll
+need a network connection for your platform to complete this setup.
 
 .. note::
    ACRN requires Clear Linux version 22140 or newer. The instructions below
@@ -54,10 +57,10 @@ need a network connection for your NUC to complete this setup.
    https://download.clearlinux.org/releases/22140/clear/clear-22140-installer.img.xz
    and follow the `Clear Linux installation guide
    <https://clearlinux.org/documentation/clear-linux/get-started/bare-metal-install>`__
-   as a starting point for installing Clear Linux onto your NUC.  Follow the recommended
-   options for choosing an **Automatic** installation type, and using the NUC's
+   as a starting point for installing Clear Linux onto your platform.  Follow the recommended
+   options for choosing an **Automatic** installation type, and using the platform's
    storage as the target device for installation (overwriting the existing data
-   and creating three partitions on the NUC's SSD drive).
+   and creating three partitions on the platform's storage drive).
 
 #. After installation is complete, boot into Clear Linux, login as
    **root**, and set a password.
@@ -97,7 +100,7 @@ need a network connection for your NUC to complete this setup.
 Add the ACRN hypervisor to the EFI Partition
 ============================================
 
-In order to boot the ACRN SOS on the NUC, you'll need to add it to the EFI
+In order to boot the ACRN SOS on the platform, you'll need to add it to the EFI
 partition. Follow these steps:
 
 #. Mount the EFI partition and verify you have the following files:
@@ -119,6 +122,13 @@ partition. Follow these steps:
       and ``*-standard``) listed on your system,
       as you will need them later.
 
+   .. note::
+      The EFI System Partition (ESP) may be different based on your hardware.
+      It will typically be something like ``/dev/mmcblk0p1`` on platforms
+      that have an on-board eMMC or ``/dev/nvme0n1p1`` if your system has
+      a non-volatile storage media attached via a PCI Express (PCIe) bus
+      (NVMe).
+
 #. Put the ``acrn.efi`` hypervisor application (included in the Clear
    Linux release) on the EFI partition with:
 
@@ -136,9 +146,7 @@ partition. Follow these steps:
 
    .. code-block:: none
 
-      # efibootmgr -c -l "\EFI\acrn\acrn.efi" -d /dev/sda1 -p 1 -L ACRN
-      # cd /mnt/EFI/org.clearlinux/
-      # cp bootloaderx64.efi bootloaderx64_origin.efi
+      # efibootmgr -c -l "\EFI\acrn\acrn.efi" -d /dev/sda -p 1 -L ACRN
 
    .. note::
       Be aware that a Clearlinux update that includes a kernel upgrade will
@@ -193,7 +201,7 @@ partition. Follow these steps:
    .. literalinclude:: ../../hypervisor/bsp/uefi/clearlinux/acrn.conf
       :caption: hypervisor/bsp/uefi/clearlinux/acrn.conf
 
-   On the NUC, copy the ``acrn.conf`` file to the EFI partition we mounted earlier:
+   On the platform, copy the ``acrn.conf`` file to the EFI partition we mounted earlier:
 
    .. code-block:: none
 
@@ -205,6 +213,9 @@ partition. Follow these steps:
 
    Use ``blkid`` to find out what your ``/dev/sda3`` ``PARTUUID`` value is.
 
+   .. note::
+      It is also possible to use the device name directly, e.g. ``root=/dev/sda3``
+
 #. Add a timeout period for Systemd-Boot to wait, otherwise it will not
    present the boot menu and will always boot the base Clear Linux
 
@@ -265,7 +276,7 @@ directory. Run it to create a network bridge:
 Set up Reference UOS
 ====================
 
-#. On your NUC, download the pre-built reference Clear Linux UOS image into your
+#. On your platform, download the pre-built reference Clear Linux UOS image into your
    (root) home directory:
 
    .. code-block:: none
@@ -295,7 +306,7 @@ Set up Reference UOS
       # umount /mnt
       # sync
 
-#. Edit and Run the launch_uos.sh script to launch the UOS.
+#. Edit and Run the ``launch_uos.sh`` script to launch the UOS.
 
    A sample `launch_uos.sh
    <https://raw.githubusercontent.com/projectacrn/acrn-hypervisor/master/devicemodel/samples/nuc/launch_uos.sh>`__