diff --git a/misc/config_tools/static_allocators/cpu_affinity.py b/misc/config_tools/static_allocators/cpu_affinity.py
new file mode 100644
index 000000000..099351a11
--- /dev/null
+++ b/misc/config_tools/static_allocators/cpu_affinity.py
@@ -0,0 +1,36 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2021 Intel Corporation. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+import sys, os
+sys.path.append(os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'library'))
+import common, board_cfg_lib
+
+def sos_cpu_affinity(etree):
+    if common.get_node("//vm[vm_type = 'SOS_VM']", etree) is None:
+        return None
+
+    if common.get_node("//vm[vm_type = 'SOS_VM' and count(cpu_affinity)]", etree) is not None:
+        return None
+
+    sos_extend_all_cpus = board_cfg_lib.get_processor_info()
+    pre_all_cpus = etree.xpath("//vm[vm_type = 'PRE_RT_VM' or vm_type = 'PRE_STD_VM' or vm_type = 'SAFETY_VM']/cpu_affinity/pcpu_id/text()")
+
+    cpus_for_sos = list(set(sos_extend_all_cpus) - set(pre_all_cpus))
+    return sorted(cpus_for_sos)
+
+def fn(board_etree, scenario_etree, allocation_etree):
+    cpus_for_sos = sos_cpu_affinity(scenario_etree)
+    if cpus_for_sos:
+        if common.get_node("//vm[vm_type = 'SOS_VM']", scenario_etree) is not None:
+            vm_id = common.get_node("//vm[vm_type = 'SOS_VM']/@id", scenario_etree)
+            allocation_sos_vm_node = common.get_node(f"/acrn-config/vm[@id='{vm_id}']", allocation_etree)
+            if allocation_sos_vm_node is None:
+                allocation_sos_vm_node = common.append_node("/acrn-config/vm", None, allocation_etree, id = vm_id)
+            if common.get_node("./vm_type", allocation_sos_vm_node) is None:
+                common.append_node("./vm_type", "SOS_VM", allocation_sos_vm_node)
+        for pcpu_id in cpus_for_sos:
+            common.append_node("./cpu_affinity/pcpu_id", str(pcpu_id), allocation_sos_vm_node)