diff --git a/openfpga/src/base/openfpga_build_fabric_template.h b/openfpga/src/base/openfpga_build_fabric_template.h
index b36903a22..193aa0fef 100644
--- a/openfpga/src/base/openfpga_build_fabric_template.h
+++ b/openfpga/src/base/openfpga_build_fabric_template.h
@@ -25,6 +25,7 @@
 #include "vtr_time.h"
 #include "write_xml_fabric_pin_physical_location.h"
 #include "write_xml_module_name_map.h"
+#include "read_xml_unique_blocks.h"
 
 /* begin namespace openfpga */
 namespace openfpga {
@@ -472,6 +473,49 @@ int write_fabric_pin_physical_location_template(
     cmd_context.option_enable(cmd, opt_verbose));
 }
 
+template <class T>
+int read_unique_blocks_template(const T& openfpga_ctx, const Command& cmd,
+                                const CommandContext& cmd_context) {
+  CommandOptionId opt_verbose = cmd.option("verbose");
+  CommandOptionId opt_file = cmd.option("file");
+  CommandOptionId opt_type = cmd.option("type");
+
+  /* Check the option '--file' is enabled or not
+   * Actually, it must be enabled as the shell interface will check
+   * before reaching this fuction
+   */
+  VTR_ASSERT(true == cmd_context.option_enable(cmd, opt_file));
+  VTR_ASSERT(false == cmd_context.option_value(cmd, opt_file).empty());
+
+  std::string file_name = cmd_context.option_value(cmd, opt_file);
+  std::string file_type = cmd_context.option_value(cmd, opt_type);
+  /* Write hierarchy to a file */
+  return read_xml_unique_blocks(file_name.c_str(), file_type.c_str(),
+                                cmd_context.option_enable(cmd, opt_verbose));
+}
+
+template <class T>
+int write_unique_blocks_template(const T& openfpga_ctx, const Command& cmd,
+                                 const CommandContext& cmd_context) {
+  CommandOptionId opt_verbose = cmd.option("verbose");
+  CommandOptionId opt_file = cmd.option("file");
+  CommandOptionId opt_type = cmd.option("type");
+
+  /* Check the option '--file' is enabled or not
+   * Actually, it must be enabled as the shell interface will check
+   * before reaching this fuction
+   */
+  VTR_ASSERT(true == cmd_context.option_enable(cmd, opt_file));
+  VTR_ASSERT(false == cmd_context.option_value(cmd, opt_file).empty());
+
+  std::string file_name = cmd_context.option_value(cmd, opt_file);
+  std::string file_type = cmd_context.option_value(cmd, opt_type);
+
+  /* Write hierarchy to a file */
+  return read_xml_unique_blocks(file_name.c_str(), file_type.c_str(),
+                                 cmd_context.option_enable(cmd, opt_verbose));
+}
+
 } /* end namespace openfpga */
 
 #endif
diff --git a/openfpga/src/base/openfpga_setup_command_template.h b/openfpga/src/base/openfpga_setup_command_template.h
index 3d178ee17..42816029c 100644
--- a/openfpga/src/base/openfpga_setup_command_template.h
+++ b/openfpga/src/base/openfpga_setup_command_template.h
@@ -924,6 +924,79 @@ ShellCommandId add_write_fabric_pin_physical_location_command_template(
   return shell_cmd_id;
 }
 
+
+/********************************************************************
+ * - Add a command to Shell environment: read_unique_blocks
+ * - Add associated options
+ * - Add command dependency
+ *******************************************************************/
+template <class T>
+ShellCommandId add_read_unique_blocks_command_template(
+  openfpga::Shell<T>& shell, const ShellCommandClassId& cmd_class_id,
+  const std::vector<ShellCommandId>& dependent_cmds, const bool& hidden) {
+  Command shell_cmd("read_unique_blocks");
+
+  /* Add an option '--file' */
+  shell_cmd.add_option(
+    "file", true,
+    "unique blocks xml file");
+
+  /* Add an option '--type' */
+  shell_cmd.add_option("type", true,
+                       "the file type of input file");
+
+  /* Add an option '--verbose' */
+  shell_cmd.add_option("verbose", false, "Show verbose outputs");
+
+  /* Add command 'compact_routing_hierarchy' to the Shell */
+  ShellCommandId shell_cmd_id = shell.add_command(
+    shell_cmd, "Preload unique blocks from xml file", hidden);
+  shell.set_command_class(shell_cmd_id, cmd_class_id);
+  shell.set_command_execute_function(shell_cmd_id, read_unique_blocks_template<T>);
+
+  /* Add command dependency to the Shell */
+  shell.set_command_dependency(shell_cmd_id, dependent_cmds);
+
+  return shell_cmd_id;
+}
+
+
+/********************************************************************
+ * - Add a command to Shell environment: write_unique_blocks
+ * - Add associated options
+ * - Add command dependency
+ *******************************************************************/
+template <class T>
+ShellCommandId add_write_unique_blocks_command_template(
+  openfpga::Shell<T>& shell, const ShellCommandClassId& cmd_class_id,
+  const std::vector<ShellCommandId>& dependent_cmds, const bool& hidden) {
+  Command shell_cmd("write_unique_blocks");
+
+  /* Add an option '--file' */
+  shell_cmd.add_option(
+    "file", true,
+    "unique blocks xml file");
+
+  /* Add an option '--type' */
+  shell_cmd.add_option("type", true,
+                       "the file type of input file");
+
+  /* Add an option '--verbose' */
+  shell_cmd.add_option("verbose", false, "Show verbose outputs");
+
+  /* Add command 'compact_routing_hierarchy' to the Shell */
+  ShellCommandId shell_cmd_id = shell.add_command(
+    shell_cmd, "Preload unique blocks from xml file", hidden);
+  shell.set_command_class(shell_cmd_id, cmd_class_id);
+  shell.set_command_execute_function(shell_cmd_id, write_unique_blocks_template<T>);
+
+  /* Add command dependency to the Shell */
+  shell.set_command_dependency(shell_cmd_id, dependent_cmds);
+
+  return shell_cmd_id;
+}
+
+
 template <class T>
 void add_setup_command_templates(openfpga::Shell<T>& shell,
                                  const bool& hidden = false) {
@@ -1175,8 +1248,21 @@ void add_setup_command_templates(openfpga::Shell<T>& shell,
   add_write_fabric_pin_physical_location_command_template<T>(
     shell, openfpga_setup_cmd_class,
     cmd_dependency_write_fabric_pin_physical_location, hidden);
-}
 
+  /********************************
+   * Command 'read_unique_blocks'
+   */
+  add_read_unique_blocks_command_template<T>(
+    shell, openfpga_setup_cmd_class, std::vector<openfpga::ShellCommandId>(), hidden);
+
+  /********************************
+   * Command 'write_unique_blocks'
+   */
+  add_write_unique_blocks_command_template<T>(
+    shell, openfpga_setup_cmd_class, std::vector<openfpga::ShellCommandId>(), hidden);
+
+  
+}
 } /* end namespace openfpga */
 
 #endif
diff --git a/openfpga/src/fabric/read_xml_unique_blocks.cpp b/openfpga/src/fabric/read_xml_unique_blocks.cpp
new file mode 100644
index 000000000..8b80f7a3e
--- /dev/null
+++ b/openfpga/src/fabric/read_xml_unique_blocks.cpp
@@ -0,0 +1,112 @@
+/********************************************************************
+ * This file includes the top-level function of this library
+ * which reads an XML of a fabric key to the associated
+ * data structures
+ *******************************************************************/
+#include <string>
+
+/* Headers from pugi XML library */
+#include "pugixml.hpp"
+#include "pugixml_util.hpp"
+
+/* Headers from vtr util library */
+#include "vtr_assert.h"
+#include "vtr_log.h"
+#include "vtr_time.h"
+
+/* Headers from libopenfpga util library */
+#include "openfpga_port_parser.h"
+
+/* Headers from libarchfpga */
+#include "arch_error.h"
+#include "read_xml_unique_blocks.h"
+#include "read_xml_util.h"
+
+/********************************************************************
+ * Parse XML codes of a <key> to an object of FabricKey
+ *******************************************************************/
+static void read_xml_unique_block_info(
+  pugi::xml_node& xml_pin_constraint, const pugiutil::loc_data& loc_data) {
+    std::string pass = "pass here";
+//   /* Create a new design constraint in the storage */
+//   RepackDesignConstraintId design_constraint_id =
+//     repack_design_constraints.create_design_constraint(
+//       RepackDesignConstraints::IGNORE_NET);
+
+//   if (false == repack_design_constraints.valid_design_constraint_id(
+//                  design_constraint_id)) {
+//     archfpga_throw(loc_data.filename_c_str(), loc_data.line(xml_pin_constraint),
+//                    "Fail to create design constraint!\n");
+//   }
+
+//   std::string pin_ctx_to_parse =
+//     get_attribute(xml_pin_constraint, "pin", loc_data).as_string();
+//   openfpga::StringToken pin_tokenizer(pin_ctx_to_parse);
+//   std::vector<std::string> pin_info = pin_tokenizer.split('.');
+//   /* Expect two contents, otherwise error out */
+//   if (pin_info.size() != 2) {
+//     std::string err_msg =
+//       std::string("Invalid content '") + pin_ctx_to_parse +
+//       std::string("' to skip, expect <pb_type_name>.<pin>\n");
+//     VTR_LOG_ERROR(err_msg.c_str());
+//     VTR_ASSERT(pin_info.size() == 2);
+//   }
+//   std::string pb_type_name = pin_info[0];
+//   openfpga::PortParser port_parser(pin_info[1]);
+//   openfpga::BasicPort curr_port = port_parser.port();
+//   if (!curr_port.is_valid()) {
+//     std::string err_msg =
+//       std::string("Invalid pin definition '") + pin_ctx_to_parse +
+//       std::string("', expect <pb_type_name>.<pin_name>[int:int]\n");
+//     VTR_LOG_ERROR(err_msg.c_str());
+//     VTR_ASSERT(curr_port.is_valid());
+//   }
+//   repack_design_constraints.set_pb_type(design_constraint_id, pb_type_name);
+//   repack_design_constraints.set_pin(design_constraint_id, curr_port);
+//   repack_design_constraints.set_net(
+//     design_constraint_id,
+//     get_attribute(xml_pin_constraint, "name", loc_data).as_string());
+}
+
+/********************************************************************
+ * Parse XML codes about <repack_design_constraints> to an object of
+ *RepackDesignConstraints
+ *******************************************************************/
+int read_xml_unique_blocks(const char* file_name, const char* file_type,
+                           bool verbose) {
+  vtr::ScopedStartFinishTimer timer("Read unique blocks xml file");
+
+//   RepackDesignConstraints repack_design_constraints;
+
+  /* Parse the file */
+  pugi::xml_document doc;
+  pugiutil::loc_data loc_data;
+
+  try {
+    loc_data = pugiutil::load_xml(doc, file_name);
+
+    pugi::xml_node xml_root =
+      get_single_child(doc, "unique_blocks", loc_data);
+
+    // size_t num_design_constraints =
+    //   std::distance(xml_root.children().begin(), xml_root.children().end());
+    // /* Reserve memory space for the region */
+    // repack_design_constraints.reserve_design_constraints(
+    //   num_design_constraints);
+
+    for (pugi::xml_node xml_block_info : xml_root.children()) {
+      /* Error out if the XML child has an invalid name! */
+      if (xml_block_info.name() == std::string("block")) {
+        read_xml_unique_block_info(xml_block_info, loc_data);
+      } else {
+        bad_tag(xml_block_info, loc_data, xml_root,
+                {"block"});
+        return 1;
+      }
+    }
+  } catch (pugiutil::XmlError& e) {
+    archfpga_throw(file_name, e.line(), "%s", e.what());
+  }
+
+  return 0;
+}
diff --git a/openfpga/src/fabric/read_xml_unique_blocks.h b/openfpga/src/fabric/read_xml_unique_blocks.h
new file mode 100644
index 000000000..cd89ff801
--- /dev/null
+++ b/openfpga/src/fabric/read_xml_unique_blocks.h
@@ -0,0 +1,16 @@
+#ifndef READ_XML_UNIQUE_BLOCKS_H
+#define READ_XML_UNIQUE_BLOCKS_H
+
+/********************************************************************
+ * Include header files that are required by function declaration
+ *******************************************************************/
+#include "pugixml.hpp"
+#include "pugixml_util.hpp"
+
+/********************************************************************
+ * Function declaration
+ *******************************************************************/
+int read_xml_unique_blocks(const char* file_name, const char* file_type,
+                           bool verbose);
+
+#endif