diff --git a/common.mk b/common.mk
index 46722d33..161f4bc0 100644
--- a/common.mk
+++ b/common.mk
@@ -146,11 +146,8 @@ FIRTOOL_TARGETS = \
 	$(FIRTOOL_FILELIST) \
 	$(FIRTOOL_BB_MODS_FILELIST)
 
-REPL_SEQ_MEM = --infer-rw --repl-seq-mem -c:$(MODEL):-o:$(FIRTOOL_SMEMS_CONF)
+SFC_REPL_SEQ_MEM = --infer-rw --repl-seq-mem -c:$(MODEL):-o:$(SFC_SMEMS_CONF)
 
-ifeq (,$(ENABLE_CUSTOM_FIRRTL_PASS))
-	EXTRA_FIRRTL_OPTIONS += $(REPL_SEQ_MEM)
-endif
 
 # DOC include start: FirrtlCompiler
 # hack: lower to low firrtl if Fixed types are found
@@ -159,8 +156,10 @@ endif
 $(FIRTOOL_TARGETS) &: $(FIRRTL_FILE) $(FINAL_ANNO_FILE) $(VLOG_SOURCES)
 ifeq (,$(ENABLE_CUSTOM_FIRRTL_PASS))
 	$(eval SFC_LEVEL := $(if $(shell grep "Fixed<" $(FIRRTL_FILE)), low, none))
+	$(eval EXTRA_FIRRTL_OPTIONS += $(if $(shell grep "Fixed<" $(FIRRTL_FILE)), $(SFC_REPL_SEQ_MEM),))
 else
 	$(eval SFC_LEVEL := low)
+	$(eval EXTRA_FIRRTL_OPTIONS += $(SFC_REPL_SEQ_MEM))
 endif
 	$(call run_scala_main,tapeout,barstools.tapeout.transforms.GenerateModelStageMain,\
 		--no-dedup \
@@ -174,8 +173,8 @@ endif
 		-X $(SFC_LEVEL) \
 		$(EXTRA_FIRRTL_OPTIONS))
 	-mv $(SFC_FIRRTL_BASENAME).lo.fir $(SFC_FIRRTL_FILE)
-	$(if $(ENABLE_CUSTOM_FIRRTL_PASS), cat $(SFC_ANNO_FILE) | jq 'del(.[] | select(.target | test("io.cpu"))?)' > /tmp/unnec-anno-deleted.sfc.anno.json,)
-	$(if $(ENABLE_CUSTOM_FIRRTL_PASS), cat /tmp/unnec-anno-deleted.sfc.anno.json > $(SFC_ANNO_FILE) && rm /tmp/unnec-anno-deleted.sfc.anno.json,)
+	@if [ "$(SFC_LEVEL)" = low ]; then cat $(SFC_ANNO_FILE) | jq 'del(.[] | select(.target | test("io.cpu"))?)' > /tmp/unnec-anno-deleted.sfc.anno.json; fi
+	@if [ "$(SFC_LEVEL)" = low ]; then cat /tmp/unnec-anno-deleted.sfc.anno.json > $(SFC_ANNO_FILE) && rm /tmp/unnec-anno-deleted.sfc.anno.json; fi
 	firtool \
 		--format=fir \
 		-O=release \
@@ -188,12 +187,13 @@ endif
 		--warn-on-unprocessed-annotations \
 		--lowering-options=emittedLineLength=2048,noAlwaysComb,disallowLocalVariables,explicitBitcast,verifLabels,locationInfoStyle=wrapInAtSquareBracket \
 		--repl-seq-mem \
-		--repl-seq-mem-circuit=$(MODEL) \
 		--repl-seq-mem-file=$(FIRTOOL_SMEMS_CONF) \
+		--repl-seq-mem-circuit=$(MODEL) \
 		--annotation-file=$(SFC_ANNO_FILE) \
 		--split-verilog \
 		-o $(OUT_DIR) \
 		$(SFC_FIRRTL_FILE)
+	-mv $(SFC_SMEMS_CONF) $(FIRTOOL_SMEMS_CONF)
 	$(SED) -i 's/.*/& /' $(FIRTOOL_SMEMS_CONF) # need trailing space for SFC macrocompiler
 # DOC include end: FirrtlCompiler
 
@@ -214,8 +214,9 @@ $(TOP_MODS_FILELIST) $(MODEL_MODS_FILELIST) $(ALL_MODS_FILELIST) $(BB_MODS_FILEL
 $(TOP_SMEMS_CONF) $(HARNESS_SMEMS_CONF) &: $(FIRTOOL_TOP_SMEMS_JSON) $(FIRTOOL_MODEL_SMEMS_JSON) $(FIRTOOL_SMEMS_CONF)
 	$(base_dir)/scripts/split-mems-conf.py \
 		--in-smems-conf $(FIRTOOL_SMEMS_CONF) \
-		--in-dut-smems-json $(FIRTOOL_TOP_SMEMS_JSON) \
-		--in-model-smems-json $(FIRTOOL_MODEL_SMEMS_JSON) \
+		--in-model-hrchy-json $(FIRTOOL_MODEL_HRCHY_JSON) \
+		--dut-module-name $(TOP) \
+		--model-module-name $(MODEL) \
 		--out-dut-smems-conf $(TOP_SMEMS_CONF) \
 		--out-model-smems-conf $(HARNESS_SMEMS_CONF)
 
diff --git a/scripts/split-mems-conf.py b/scripts/split-mems-conf.py
index 89f338b1..b9eb7966 100755
--- a/scripts/split-mems-conf.py
+++ b/scripts/split-mems-conf.py
@@ -3,6 +3,7 @@
 import os
 import json
 import argparse
+import sys
 from typing import List, Optional
 
 # Schema of json emitted by circt
@@ -23,43 +24,73 @@ from typing import List, Optional
 }
 """
 
+sys.setrecursionlimit(100)
+
+
+
+# Performing DFS recursively is not a problem here since the modules that
+# we are interested in are close to the root of the module hierarchy
+def dfs_find_root(tree, module_name):
+  if tree['module_name'] == module_name:
+    return tree
+  if len(tree['instances']) == 0:
+    exit(0)
+  for c in tree['instances']:
+    ret = dfs_find_root(c, module_name)
+    if ret is not None:
+      return ret
+  return None
+
+
+def bfs_collect_module(tree):
+  output = set()
+  q = [(tree['instance_name'], tree['module_name'], tree['instances'])]
+
+  while len(q) != 0:
+    front = q[0]
+    q.pop(0)
+
+    (inst, mod, child) = front
+    output.add(mod)
+    for c in child:
+      q.append((c['instance_name'], c['module_name'], c['instances']))
+  return output
+
+
 if __name__ == "__main__":
-    parser = argparse.ArgumentParser(description='Use CIRCT (firtool) smems JSONs to create DUT and test harness smems confs')
-    parser.add_argument('--in-smems-conf', type=str, required=True, help='Overall smems conf file that contains all memory definitions')
-    parser.add_argument('--in-dut-smems-json', type=str, required=True, help='JSON indicating which mem modules are in the DUT')
-    parser.add_argument('--in-model-smems-json', type=str, required=True, help='JSON indicating which mem modules are in the top-most level module (but not in the DUT)')
-    parser.add_argument('--out-dut-smems-conf', type=str, required=True, help='Smems conf with only DUT mem module definitions')
-    parser.add_argument('--out-model-smems-conf', type=str, required=True, help='Smems conf with only top-most level mem module definitions (not including DUT modules)')
-    args = parser.parse_args()
+  parser = argparse.ArgumentParser(description='Use CIRCT (firtool) model-hrchy JSONs to create DUT and test harness smems confs or ')
+  parser.add_argument('--in-smems-conf', type=str, required=True, help='Overall smems conf file that contains all memory definitions')
+  parser.add_argument('--in-model-hrchy-json', type=str, required=True, help='JSON indicating which mem modules are in the DUT')
+  parser.add_argument('--dut-module-name', type=str, required=True, help='Module name of the DUT')
+  parser.add_argument('--model-module-name', type=str, required=True, help='Module name of the model')
+  parser.add_argument('--out-dut-smems-conf', type=str, required=True, help='Smems conf with only DUT mem module definitions')
+  parser.add_argument('--out-model-smems-conf', type=str, required=True, help='Smems conf with only top-most level mem module definitions (not including DUT modules)')
+  args = parser.parse_args()
 
-    with open(args.in_smems_conf) as isc, \
-         open(args.in_dut_smems_json) as idsj, \
-         open(args.in_model_smems_json) as itsj:
-        idsj_data = json.load(idsj)
-        itsj_data  = json.load(itsj)
+  with open(args.in_smems_conf) as isc, \
+       open(args.in_model_hrchy_json) as imhj:
+    imhj_data = json.load(imhj)
 
-        dut_mods = set()
-        for e in idsj_data:
-            dut_mods.add(e['module_name'])
+    dut_root = dfs_find_root(imhj_data, args.dut_module_name)
+    dut_submodules = bfs_collect_module(dut_root)
 
-        model_mods = set()
-        for e in itsj_data:
-            model_mods.add(e['module_name'])
+    model_root = dfs_find_root(imhj_data, args.model_module_name)
+    model_submodules = bfs_collect_module(model_root)
 
-        with open(args.out_dut_smems_conf, "w") as odsc, \
-             open(args.out_model_smems_conf, "w") as otsc:
-            for l in isc:
-                sl = l.split()
+    with open(args.out_dut_smems_conf, "w") as odsc, \
+         open(args.out_model_smems_conf, "w") as otsc:
+      for l in isc:
+        sl = l.split()
 
-                # the line can't be split then stop immediately (normally an empty file)
-                if len(sl) > 2:
-                    name = sl[1]
+        # the line can't be split then stop immediately (normally an empty file)
+        if len(sl) > 2:
+          name = sl[1]
 
-                    if name in dut_mods:
-                        odsc.write(l)
-                    elif name in model_mods:
-                        otsc.write(l)
-                    else:
-                        assert False, "Unable to find smem CONF module in firtool emitted JSON files."
-                else:
-                    exit(0)
+          if name in dut_submodules:
+            odsc.write(l)
+          elif name in model_submodules:
+            otsc.write(l)
+          else:
+            assert False, "Unable to find smem CONF module in firtool emitted JSON files."
+        else:
+            exit(0)
diff --git a/tools/barstools b/tools/barstools
index 899387f4..e340f124 160000
--- a/tools/barstools
+++ b/tools/barstools
@@ -1 +1 @@
-Subproject commit 899387f4fb54279a8d5c0a16e543c2cc6e60f6b8
+Subproject commit e340f1240a2c5feeb85160a7f81a32496916a7c4
diff --git a/variables.mk b/variables.mk
index 9c68d594..a457a813 100644
--- a/variables.mk
+++ b/variables.mk
@@ -167,6 +167,7 @@ FIRTOOL_TOP_SMEMS_JSON = $(OUT_DIR)/metadata/seq_mems.json
 FIRTOOL_MODEL_SMEMS_JSON = $(OUT_DIR)/metadata/tb_seq_mems.json
 
 # macrocompiler smems in/output
+SFC_SMEMS_CONF ?= $(build_dir)/$(long_name).sfc.mems.conf
 TOP_SMEMS_CONF ?= $(build_dir)/$(long_name).top.mems.conf
 TOP_SMEMS_FILE ?= $(OUT_DIR)/$(long_name).top.mems.v
 TOP_SMEMS_FIR  ?= $(build_dir)/$(long_name).top.mems.fir