doc: revert Ubuntu24.04 support in GSG

Since Ubuntu24.04 requires 6.8 kernel(as shown in Ubuntu linux kernel
release lifecycle), we need to revert the ubuntu24.04 support in GSG to
suit our 6.1 acrn kernel.

Tracked-On: #8664
Signed-off-by: Jiayuan Yang <jiayuan.yang@intel.com>

doc/getting-started/getting-started.rst

@@ -38,15 +38,15 @@ Before you begin, make sure your machines have the following prerequisites:
 
 * Software specifications
 
-  - Ubuntu Desktop 24.04 LTS (ACRN development is not supported on Windows.)
+  - Ubuntu Desktop 22.04 LTS (ACRN development is not supported on Windows.)
 
 **Target system**:
 
 * Hardware specifications
 
   - Target board (see :ref:`hardware_tested`)
-  - Ubuntu Desktop 24.04 LTS bootable USB disk: download the latest `Ubuntu
-    Desktop 24.04 LTS ISO image <https://releases.ubuntu.com/noble/>`__ and
+  - Ubuntu Desktop 22.04 LTS bootable USB disk: download the latest `Ubuntu
+    Desktop 22.04 LTS ISO image <https://releases.ubuntu.com/jammy/>`__ and
     follow the `Ubuntu documentation
     <https://ubuntu.com/tutorials/create-a-usb-stick-on-ubuntu#1-overview>`__
     for creating the USB disk.
@@ -75,7 +75,7 @@ Prepare the Development Computer
 To set up the ACRN build environment on the development computer:
 
 #. On the development computer, run the following command to confirm that Ubuntu
-   Desktop 24.04 is running:
+   Desktop 22.04 is running:
 
    .. code-block:: bash
 
@@ -119,8 +119,8 @@ To set up the ACRN build environment on the development computer:
            xsltproc clang-format bc libpixman-1-dev libsdl2-dev libegl-dev \
            libgles-dev libdrm-dev gnu-efi libelf-dev liburing-dev \
            build-essential git-buildpackage devscripts dpkg-dev equivs lintian \
-           apt-utils pristine-tar dh-python acpica-tools
-      sudo pip3 install "elementpath==2.5.0" lxml "xmlschema==1.9.2" defusedxml tqdm  
+           apt-utils pristine-tar dh-python acpica-tools python3-tqdm \
+           python3-elementpath python3-lxml python3-xmlschema python3-defusedxml
       
 
 #. Get the ACRN hypervisor and ACRN kernel source code, and check out the
@@ -172,7 +172,7 @@ To set up the target hardware environment:
 
 #. Connect the monitor and power supply cable.
 
-#. Connect the target system to the LAN with the Ethernet cable.
+#. Connect the target system to the LAN with the Ethernet cable or wifi.
 
 Example of a target system with cables connected:
 
@@ -182,13 +182,13 @@ Example of a target system with cables connected:
 Install OS on the Target
 ============================
 
-The target system needs Ubuntu Desktop 24.04 LTS to run the Board Inspector
+The target system needs Ubuntu Desktop 22.04 LTS to run the Board Inspector
 tool. You can read the full instructions to download, create a bootable USB
 drive, and `Install Ubuntu desktop
 <https://ubuntu.com/tutorials/install-ubuntu-desktop#1-overview>`_ on the Ubuntu
 site.  We'll provide a summary here:
 
-To install Ubuntu 24.04:
+To install Ubuntu 22.04:
 
 #. Insert the Ubuntu bootable USB disk into the target system.
 
@@ -248,9 +248,10 @@ Configure Target BIOS Settings
 #. Boot your target and enter the BIOS configuration editor.
 
    Tip: When you are booting your target, you'll see an option (quickly) to
-   enter the BIOS configuration editor, typically by pressing :kbd:`F2` or :kbd:`DEL` during
-   the boot and before the GRUB menu (or Ubuntu login screen) appears. If you
-   are not quick enough, you can still choose ``UEFI settings`` in the GRUB menu.
+   enter the BIOS configuration editor, typically by pressing :kbd:`F2` 
+   or :kbd:`DEL` during the boot and before the GRUB menu (or Ubuntu login
+   screen) appears. If you are not quick enough, you can still choose
+   ``UEFI settings`` in the GRUB menu or just reboot the system to try again.
 
 #. Configure these BIOS settings:
 
@@ -467,9 +468,9 @@ post-launched User VM. Each User VM has its own launch script.
    #. Confirm that the **VM type** is ``Standard``. In the previous step,
       ``STD`` in the VM name is short for Standard.
 
-   #. Scroll down to **Memory size (MB)** and change the value to ``4096``. For
-      this example, we will use Ubuntu 24.04 to boot the post-launched VM.
-      Ubuntu 24.04 needs at least 4096 MB to boot.
+   #. Scroll down to **Memory size (MB)** and change the value to ``2048``. For
+      this example, we will use Ubuntu 22.04 to boot the post-launched VM.
+      Ubuntu 22.04 needs at least 2048 MB to boot.
 
    #. For **Physical CPU affinity**, select pCPU ID ``0``, then click **+** and
       select pCPU ID ``1`` to affine (or pin) the VM to CPU cores 0 and 1. (That will
@@ -479,17 +480,17 @@ post-launched User VM. Each User VM has its own launch script.
       default options. 
 
    #. For **Virtio block device**, click **+** and enter
-      ``/home/acrn/acrn-work/user-vm1.img``. This parameter
+      ``/home/acrn/acrn-work/ubuntu-22.04.2-desktop-amd64.iso``. This parameter
       specifies the VM's OS image and its location on the target system. Later
-      in this guide, you will create the image file to that directory. (If you used
+      in this guide, you will save the ISO file to that directory. (If you used
       a different username when installing Ubuntu on the target system, here's
       where you'll need to change the ``acrn`` username to the username you used.)
 
-   .. image:: images/configurator-postvm01.png
+   .. image:: images/configurator_postvm01.png
       :align: center
       :class: drop-shadow
 
-   .. image:: images/configurator-postvm02.png
+   .. image:: images/configurator_postvm02.png
       :align: center
       :class: drop-shadow
 
@@ -574,7 +575,6 @@ Build ACRN
       ls *acrn-service-vm*.deb  
          linux-headers-6.1.80-acrn-service-vm_6.1.80-acrn-service-vm-1_amd64.deb
          linux-image-6.1.80-acrn-service-vm_6.1.80-acrn-service-vm-1_amd64.deb
-         linux-image-6.1.80-acrn-service-vm-dbg_6.1.80-acrn-service-vm-1_amd64.deb
          linux-libc-dev_6.1.80-acrn-service-vm-1_amd64.deb
 
 #. Use the ``scp`` command to copy files from your development computer to the
@@ -688,24 +688,21 @@ The ACRN hypervisor boots the Ubuntu Service VM automatically.
 Launch the User VM
 *******************
 
-#. On the target system, download the Ubuntu cloud images ``noble-server-cloudimg-amd64.img`` 
-   for the User VM into the ``~/acrn-work/`` directory (the location we said
-   in the ACRN Configurator for the scenario configuration for the VM): 
+#. On the target system, use the web browser to visit the `official Ubuntu website <https://releases.ubuntu.com/jammy/>`__ and
+   get the Ubuntu Desktop 22.04 LTS ISO image
+   ``ubuntu-22.04.2-desktop-amd64.iso`` for the User VM. (The same image you
+   specified earlier in the ACRN Configurator UI.) Alternatively, instead of
+   downloading it again, you could use ``scp`` to copy the ISO
+   image file from the development system to the ``~/acrn-work`` directory on the target system.
 
-   .. code-block:: bash
-      
-      cd ~/acrn-work/
-      wget https://cloud-images.ubuntu.com/noble/current/noble-server-cloudimg-amd64.img ./
-
-#. We need to do some steps before booting into cloud image User VM: Set up username and password both to ``acrn``; 
-   Change the image format to ``raw`` and change the image size:  
+#. If you downloaded the ISO file on the target system, copy it from the
+   Downloads directory to the ``~/acrn-work/`` directory (the location we said
+   in the ACRN Configurator for the scenario configuration for the VM), for
+   example:
 
    .. code-block:: bash
 
-      sudo apt install qemu-utils guestfs-tools
-      sudo virt-customize -a ./noble-server-cloudimg-amd64.img --run-command 'useradd -m -s /bin/bash acrn' --run-command 'echo "acrn:acrn" | chpasswd' --run-command 'systemctl disable systemd-networkd-wait-online.service'
-      qemu-img convert -f qcow2 -O raw ./noble-server-cloudimg-amd64.img ./user-vm1.img
-      qemu-img -f raw ./user-vm1.img 16G
+      cp ~/Downloads/ubuntu-22.04.2-desktop-amd64.iso ~/acrn-work
 
 #. Launch the User VM:
 
@@ -720,9 +717,34 @@ Launch the User VM
    
    .. code-block:: console
 
-      Ubuntu 24.04 LTS ubuntu hvc0
+      Welcome to Ubuntu 22.04.2 LTS (GNU/Linux 5.19.0-32-generic x86_64)
 
-      ubuntu login:
+      * Documentation:  https://help.ubuntu.com
+      * Management:     https://landscape.canonical.com
+      * Support:        https://ubuntu.com/advantage
+
+      Expanded Security Maintenance for Applications is not enabled.
+
+      0 updates can be applied immediately.
+
+      Enable ESM Apps to receive additional future security updates.
+      See https://ubuntu.com/esm or run: sudo pro status
+
+
+      The list of available updates is more than a week old.
+      To check for new updates run: sudo apt update
+
+      The programs included with the Ubuntu system are free software;
+      the exact distribution terms for each program are described in the
+      individual files in /usr/share/doc/*/copyright.
+
+      Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
+      applicable law.
+
+      To run a command as administrator (user "root"), use "sudo <command>".
+      See "man sudo_root" for details.
+
+      ubuntu@ubuntu:~$
 
 #. This User VM and the Service VM are running different Ubuntu images. Use this
    command to see that the User VM is running the downloaded Ubuntu image:
@@ -730,7 +752,7 @@ Launch the User VM
    .. code-block:: console
 
       acrn@ubuntu:~$ uname -r
-      6.8.0-36-generic
+      5.19.0-32-generic
 
    Then open a new terminal window and use the command to see that the Service
    VM is running the ``acrn-kernel`` Service VM image: