multi-arch: note on new config and improvements (#491)

diff --git a/source/_global.rst b/source/_global.rst
index f5819b2..280926d 100644
--- a/source/_global.rst
+++ b/source/_global.rst
@@ -33,11 +33,12 @@
 .. |sysvm64-name-ovm|    replace:: systemvm-ovm-4.20.0-x86_64
 
 .. Latest version systemvm template URL
-.. |sysvm64-url-xen|    replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-xen.vhd.bz2
-.. |sysvm64-url-kvm|    replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-kvm.qcow2.bz2
-.. |sysvm64-url-vmware| replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-vmware.ova
-.. |sysvm64-url-hyperv| replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-hyperv.vhd.zip
-.. |sysvm64-url-ovm|    replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-ovm.raw.bz2
+.. |sysvm64-url-xen|            replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-xen.vhd.bz2
+.. |sysvm64-url-kvm|            replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-kvm.qcow2.bz2
+.. |sysvm64-url-kvm-aarch64|    replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-aarch64-kvm.qcow2.bz2
+.. |sysvm64-url-vmware|         replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-vmware.ova
+.. |sysvm64-url-hyperv|         replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-hyperv.vhd.zip
+.. |sysvm64-url-ovm|            replace:: http://download.cloudstack.org/systemvm/4.20/systemvmtemplate-4.20.0-x86_64-ovm.raw.bz2
 
 .. Images
 
diff --git a/source/adminguide/systemvm.rst b/source/adminguide/systemvm.rst
index 756ae2f..d88561e 100644
--- a/source/adminguide/systemvm.rst
+++ b/source/adminguide/systemvm.rst
@@ -27,7 +27,7 @@
 The System VMs come from a single Template. The System VM has the
 following characteristics:
 
--  Debian 10.8(buster), 4.19.0 kernel with the latest security
+-  Debian 12(bookwork), 6.1.0 kernel with the latest security
    patches from the Debian security APT repository
 
 -  Has a minimal set of packages installed thereby reducing the attack
@@ -46,6 +46,42 @@
 -  Latest version of JRE from Sun/Oracle ensures improved security and
    speed
 
+Starting with 4.20.0 release, the following architectures are supported for KVM
+hypervisor:
+
+- Intel/AMD 64-bit (x86_64)
+
+- ARM 64-bit (aarch64)
+
+Other hypervisors only support Intel/AMD 64-bit (x86_64)
+
+
+System VM Template bundled with packages
+----------------------------------------
+
+The System VM Template is bundled with the official release DEB and RPM
+cloudstack-management packages for Intel/AMD 64-bit architecture and the
+following hypervisors:
+
+- KVM
+
+- VMware
+
+- XenServer
+
+Currently, the ARM 64-bit template(s) are not bundled with the packages.
+
+During zone deployment and upgrade, the required templates, i.e., the
+templates for hypervisor and architecture which are in use in the zone
+if not already present will be automatically registered and seeded on
+the secondary storage.
+
+ARM 64-bit template(s) will be downloaded from the official repository
+and the same workflow for the registration and seeding will be used. If
+the automatic download and seeding of ARM 64-bit template fails, the
+template can be manually registered in a multi-architecture zone or
+will need manual registration and seeding in a ARM 64-bit only zone.
+
 
 Changing the Default System VM Template
 ---------------------------------------
@@ -58,18 +94,19 @@
 
    .. cssclass:: table-striped table-bordered table-hover
 
-   ==========  ================================================================================================
-   Hypervisor  Download Location
-   ==========  ================================================================================================
-   XenServer   |sysvm64-url-xen|
-   KVM         |sysvm64-url-kvm|
-   VMware      |sysvm64-url-vmware|
-   Hyper-V     |sysvm64-url-hyperv|
-   ==========  ================================================================================================
+   ==========  ============  ==================================================================================
+   Hypervisor  Architecture  Download Location
+   ==========  ============  ==================================================================================
+   XenServer   x86_64        |sysvm64-url-xen|
+   KVM         x86_64        |sysvm64-url-kvm|
+   KVM         aarch64       |sysvm64-url-kvm-aarch64|
+   VMware      x86_64        |sysvm64-url-vmware|
+   Hyper-V     x86_64        |sysvm64-url-hyperv|
+   ==========  ============  ==================================================================================
 
 #. As an administrator, log in to the CloudStack UI
 
-#. Register the 64 bit Template.
+#. Register the 64-bit Template.
 
    For example: KVM64bitTemplate
 
@@ -89,6 +126,11 @@
    Any new virtual router created in this Zone automatically picks up
    this Template.
 
+#. When using multiple architectures in the Zone, same name can be used
+   for the templates for the different architectures and same hypervisor
+   to allow deployment across them depending on the compute capacity and
+   the zone setting - *system.vm.preferred.architecture*
+
 #. Restart the Management Server.
 
 Accessing System VMs
diff --git a/source/installguide/configuration.rst b/source/installguide/configuration.rst
index 93101fd..2767fa3 100644
--- a/source/installguide/configuration.rst
+++ b/source/installguide/configuration.rst
@@ -287,6 +287,9 @@
 
    -  `“Advanced Zone Configuration” <#advanced-zone-configuration>`_
 
+.. note::
+      Since CloudStack 4.20.1, it is possible to specify the preferred architecture type for a zone for deployment of system VM including virtual routers. Zone setting - *system.vm.preferred.architecture* can be updated for this. The server will first try deployment on the preferred architecture and if it fails then will attempt on other architecture hosts.
+      Administrator can also register ROUTING template with the same name for different architectures to allow deployment across them depending on the compute capacity. For other system VMs, server will attempt deployment using different architecture templates available.
 
 Basic Zone Configuration
 ~~~~~~~~~~~~~~~~~~~~~~~~