diff --git a/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst b/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst
index 9bc9c6334..2722dc46d 100644
--- a/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst
+++ b/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst
@@ -111,6 +111,10 @@ write_gsb_to_xml
     Specify the output directory of the XML files. Each GSB will be written to an indepedent XML file
     For example, ``--file /temp/gsb_output``
 
+  .. option:: --unique
+
+    Only output unique GSBs to XML files
+
   .. option:: --verbose
 
     Show verbose log
diff --git a/openfpga/src/annotation/device_rr_gsb.cpp b/openfpga/src/annotation/device_rr_gsb.cpp
index c10a9df9c..9abbea351 100644
--- a/openfpga/src/annotation/device_rr_gsb.cpp
+++ b/openfpga/src/annotation/device_rr_gsb.cpp
@@ -86,6 +86,13 @@ size_t DeviceRRGSB::get_num_gsb_unique_module() const {
   return gsb_unique_module_.size();
 } 
 
+/* Get a rr switch block which a unique mirror */ 
+const RRGSB& DeviceRRGSB::get_gsb_unique_module(const size_t& index) const {
+  VTR_ASSERT (validate_gsb_unique_module_index(index));
+  
+  return rr_gsb_[gsb_unique_module_[index].x()][gsb_unique_module_[index].y()];
+}
+
 /* Get a rr switch block which a unique mirror */ 
 const RRGSB& DeviceRRGSB::get_sb_unique_module(const size_t& index) const {
   VTR_ASSERT (validate_sb_unique_module_index(index));
@@ -461,6 +468,11 @@ bool DeviceRRGSB::validate_coordinate(const vtr::Point<size_t>& coordinate) cons
   return (coordinate.y() < rr_gsb_[coordinate.x()].capacity());
 } 
 
+/* Validate if the index in the range of unique_mirror vector*/
+bool DeviceRRGSB::validate_gsb_unique_module_index(const size_t& index) const { 
+  return (index < gsb_unique_module_.size());
+}
+
 /* Validate if the index in the range of unique_mirror vector*/
 bool DeviceRRGSB::validate_sb_unique_module_index(const size_t& index) const { 
   return (index < sb_unique_module_.size());
diff --git a/openfpga/src/annotation/device_rr_gsb.h b/openfpga/src/annotation/device_rr_gsb.h
index 4d8aad401..290322079 100644
--- a/openfpga/src/annotation/device_rr_gsb.h
+++ b/openfpga/src/annotation/device_rr_gsb.h
@@ -32,6 +32,7 @@ class DeviceRRGSB {
     const RRGSB& get_gsb(const size_t& x, const size_t& y) const; /* Get a rr switch block in the array with a coordinate */
     size_t get_num_gsb_unique_module() const; /* get the number of unique mirrors of GSB */
     size_t get_num_sb_unique_module() const; /* get the number of unique mirrors of switch blocks */
+    const RRGSB& get_gsb_unique_module(const size_t& index) const; /* Get a rr-gsb which is a unique mirror */ 
     const RRGSB& get_sb_unique_module(const size_t& index) const; /* Get a rr switch block which a unique mirror */ 
     const RRGSB& get_sb_unique_module(const vtr::Point<size_t>& coordinate) const; /* Get a rr switch block which a unique mirror */ 
     const RRGSB& get_cb_unique_module(const t_rr_type& cb_type, const size_t& index) const; /* Get a rr switch block which a unique mirror */ 
@@ -58,6 +59,7 @@ class DeviceRRGSB {
   private: /* Validators */
     bool validate_coordinate(const vtr::Point<size_t>& coordinate) const; /* Validate if the (x,y) is the range of this device */
     bool validate_side(const e_side& side) const; /* validate if side is in the range of unique_side_module_ */
+    bool validate_gsb_unique_module_index(const size_t& index) const; /* Validate if the index in the range of unique_mirror vector*/
     bool validate_sb_unique_module_index(const size_t& index) const; /* Validate if the index in the range of unique_mirror vector*/
     bool validate_cb_unique_module_index(const t_rr_type& cb_type, const size_t& index) const; /* Validate if the index in the range of unique_mirror vector*/
     bool validate_cb_type(const t_rr_type& cb_type) const;
diff --git a/openfpga/src/annotation/write_xml_device_rr_gsb.cpp b/openfpga/src/annotation/write_xml_device_rr_gsb.cpp
index 8aa8fb3b6..566d706a8 100644
--- a/openfpga/src/annotation/write_xml_device_rr_gsb.cpp
+++ b/openfpga/src/annotation/write_xml_device_rr_gsb.cpp
@@ -184,6 +184,7 @@ void write_rr_switch_block_to_xml(const std::string fname_prefix,
 void write_device_rr_gsb_to_xml(const char* sb_xml_dir, 
                                 const RRGraph& rr_graph,
                                 const DeviceRRGSB& device_rr_gsb,
+                                const bool& unique,
                                 const bool& verbose) {
   std::string xml_dir_name = format_dir_path(std::string(sb_xml_dir));
 
@@ -195,11 +196,22 @@ void write_device_rr_gsb_to_xml(const char* sb_xml_dir,
   size_t gsb_counter = 0;
 
   /* For each switch block, an XML file will be outputted */
-  for (size_t ix = 0; ix < sb_range.x(); ++ix) {
-    for (size_t iy = 0; iy < sb_range.y(); ++iy) {
-      const RRGSB& rr_gsb = device_rr_gsb.get_gsb(ix, iy);
+  if (unique) {
+    /* Only output unique GSB modules */
+    VTR_LOG("Only output unique GSB modules to XML\n");
+    for (size_t igsb = 0; igsb < device_rr_gsb.get_num_gsb_unique_module(); ++igsb) {
+      const RRGSB& rr_gsb = device_rr_gsb.get_gsb_unique_module(igsb);
       write_rr_switch_block_to_xml(xml_dir_name, rr_graph, rr_gsb, verbose);
       gsb_counter++;
+    } 
+  } else {
+    /* Output all GSB instances in the fabric (some instances may share the same module) */
+    for (size_t ix = 0; ix < sb_range.x(); ++ix) {
+      for (size_t iy = 0; iy < sb_range.y(); ++iy) {
+        const RRGSB& rr_gsb = device_rr_gsb.get_gsb(ix, iy);
+        write_rr_switch_block_to_xml(xml_dir_name, rr_graph, rr_gsb, verbose);
+        gsb_counter++;
+      }
     }
   }
 
diff --git a/openfpga/src/annotation/write_xml_device_rr_gsb.h b/openfpga/src/annotation/write_xml_device_rr_gsb.h
index a6655ab22..9d558d1f1 100644
--- a/openfpga/src/annotation/write_xml_device_rr_gsb.h
+++ b/openfpga/src/annotation/write_xml_device_rr_gsb.h
@@ -18,6 +18,7 @@ namespace openfpga {
 void write_device_rr_gsb_to_xml(const char* sb_xml_dir,
                                 const RRGraph& rr_graph,
                                 const DeviceRRGSB& device_rr_gsb,
+                                const bool& unique,
                                 const bool& verbose);
 
 } /* end namespace openfpga */
diff --git a/openfpga/src/base/openfpga_setup_command.cpp b/openfpga/src/base/openfpga_setup_command.cpp
index 517ed364a..7293c82e7 100644
--- a/openfpga/src/base/openfpga_setup_command.cpp
+++ b/openfpga/src/base/openfpga_setup_command.cpp
@@ -209,6 +209,9 @@ ShellCommandId add_openfpga_write_gsb_command(openfpga::Shell<OpenfpgaContext>&
   shell_cmd.set_option_short_name(opt_file, "f");
   shell_cmd.set_option_require_value(opt_file, openfpga::OPT_STRING);
 
+  /* Add an option '--unique' */
+  shell_cmd.add_option("unique", false, "Only output unique GSB blocks");
+
   /* Add an option '--verbose' */
   shell_cmd.add_option("verbose", false, "Show verbose outputs");
 
diff --git a/openfpga/src/base/openfpga_write_gsb.cpp b/openfpga/src/base/openfpga_write_gsb.cpp
index cdb833c75..0a783cc01 100644
--- a/openfpga/src/base/openfpga_write_gsb.cpp
+++ b/openfpga/src/base/openfpga_write_gsb.cpp
@@ -33,6 +33,7 @@ int write_gsb(const OpenfpgaContext& openfpga_ctx,
   VTR_ASSERT(true == cmd_context.option_enable(cmd, opt_file));
   VTR_ASSERT(false == cmd_context.option_value(cmd, opt_file).empty());
 
+  CommandOptionId opt_unique = cmd.option("unique");
   CommandOptionId opt_verbose = cmd.option("verbose");
 
   std::string sb_file_name = cmd_context.option_value(cmd, opt_file);
@@ -40,6 +41,7 @@ int write_gsb(const OpenfpgaContext& openfpga_ctx,
   write_device_rr_gsb_to_xml(sb_file_name.c_str(),
                              g_vpr_ctx.device().rr_graph,
                              openfpga_ctx.device_rr_gsb(),
+                             cmd_context.option_enable(cmd, opt_unique),
                              cmd_context.option_enable(cmd, opt_verbose));
 
   /* TODO: should identify the error code from internal function execution */