diff --git a/doc/getting-started/apl-nuc.rst b/doc/getting-started/apl-nuc.rst
index 3c6e16af9..18dd7aacc 100644
--- a/doc/getting-started/apl-nuc.rst
+++ b/doc/getting-started/apl-nuc.rst
@@ -166,7 +166,7 @@ partition. Follow these steps:
       double-check the platform boot order using ``efibootmgr -v`` and
       modify it if needed.
 
-   The ACRN hypervisor (``acrn.efi``) accepts two command-line parameters that
+   The ACRN hypervisor (``acrn.efi``) accepts three command-line parameters that
    tweak its behaviour:
 
    1. ``bootloader=``: this sets the EFI executable to be loaded once the hypervisor
@@ -178,8 +178,13 @@ partition. Follow these steps:
 
       #. ``uart=disabled``: this disables the serial port completely
       #. ``uart=bdf@<BDF value>``:  this sets the PCI serial port based on its BDF.
-         For example, use ``bdf@0:18.2`` for a BDF of 0:18.2 ttyS2.
+         For example, use ``bdf@0:18.1`` for a BDF of 0:18.1 ttyS1.
       #. ``uart=port@<port address>``: this sets the serial port address
+   #. ``vuart=ttySn@irqN``: this tells the hypervisor which virtual serial device SOS
+      will use and its IRQ number. This is used to avoid conflict with SOS passthrough  
+      devices' interrupt. If UART is set to ttyS1, and its native IRQ is 5, you'd better
+      set ``vuart=ttyS1@irq5`` (Use 'dmesg | grep tty' to get IRQ information).
+      Also set ``console=ttyS1`` in ``acrn.conf`` to match the SOS boot args.
 
    Here is a more complete example of how to configure the EFI firmware to load the ACRN
    hypervisor and set these parameters.
diff --git a/doc/getting-started/up2.rst b/doc/getting-started/up2.rst
index 8d6007a3d..4cbd46251 100644
--- a/doc/getting-started/up2.rst
+++ b/doc/getting-started/up2.rst
@@ -75,13 +75,15 @@ You will need to keep these in mind in a few places:
   .. code-block:: none
 
      # efibootmgr -c -l "\EFI\acrn\acrn.efi" -d /dev/mmcblk0 -p 1 -L "ACRN Hypervisor" \
-         -u "bootloader=\EFI\org.clearlinux\bootloaderx64.efi uart=bdf@0:18.1"
+         -u "bootloader=\EFI\org.clearlinux\bootloaderx64.efi uart=bdf@0:18.1 vuart=ttyS1@irq5"
 
 UP2 serial port setting
 =======================
 
-The serial port in the 40-pin HAT connector is located at ``serial PCI BDF 0:18.1``.
+The serial port (ttyS1) in the 40-pin HAT connector is located at ``serial PCI BDF 0:18.1``.
 You can check this from the ``lspci`` output from the initial Clearlinux installation.
+Also you can use ``dmesg | grep tty`` to get its IRQ infomation for vuart setting; and update
+SOS bootargs ``console=ttyS1`` in acrn.conf to match with vuart setting.
 
 .. code-block:: none
 
@@ -89,7 +91,11 @@ You can check this from the ``lspci`` output from the initial Clearlinux install
    00:18.0 . Series HSUART Controller #1 (rev 0b)
    00:18.1 . Series HSUART Controller #2 (rev 0b)
 
-The second entry associated with ``00:18.1`` is the one on the 40-pin HAT connector.
+   # dmesg | grep tty
+   dw-apb-uart.8: ttyS0 at MMIO 0x91524000 (irq = 4, base_baud = 115200) is a 16550A
+   dw-apb-uart.9: ttyS1 at MMIO 0x91522000 (irq = 5, base_baud = 115200) is a 16550A
+
+The second entry associated with ``00:18.1 @irq5`` is the one on the 40-pin HAT connector.
 
 UP2 block device
 ================