diff --git a/scripts/00_env.sh b/scripts/00_env.sh
index 975ece5..6e8a047 100755
--- a/scripts/00_env.sh
+++ b/scripts/00_env.sh
@@ -2,41 +2,40 @@
 set -eu
 
 ROOT="/home/carlos/projects/gem5"
+SRC="$ROOT/gem5src/gem5"
 IOT="$ROOT/iot"
-DATA="$ROOT/gem5-data"                     # persistent store (your symlink)
-RUN="$ROOT/gem5-run"                       # workloads
-CFG="$ROOT/scripts/hetero_big_little.py"   # gem5 config script
+DATA="$ROOT/gem5-data"                   # persistent (symlink to /mnt/storage/…)
+RUN="$ROOT/gem5-run"                     # workloads
+CFG="$ROOT/scripts/hetero_big_little.py" # gem5 config
 
-# auto-detect gem5.opt (ARM or ARM64)
-if [ -x "$ROOT/build/ARM/gem5.opt" ]; then
-  GEM5="$ROOT/build/ARM/gem5.opt"
-elif [ -x "$ROOT/gem5-build/ARM/gem5.opt" ]; then
-  GEM5="$ROOT/gem5-build/ARM/gem5.opt"
-elif [ -x "$ROOT/gem5-build/ARM64/gem5.opt" ]; then
-  GEM5="$ROOT/gem5-build/ARM64/gem5.opt"
-else
-  echo "[env] gem5.opt not found. Build it with:"
-  echo "      scons build/ARM/gem5.opt -j\$(nproc)"
-  exit 2
+# --- build target (ARM by default) ---
+GEM5_BIN="$ROOT/build/ARM/gem5.opt"
+
+# --- auto-build if missing (non-interactive: sends newline to accept hooks prompt) ---
+if [ ! -x "$GEM5_BIN" ]; then
+  echo "[env] gem5.opt not found, building at $GEM5_BIN via $SRC ..."
+  ( cd "$SRC" && printf '\n' | scons "$GEM5_BIN" -j"$(nproc)" )
 fi
 
-# primary outputs in gem5-data, mirrored into iot/
+# verify binary
+[ -x "$GEM5_BIN" ] || { echo "[env] build failed: $GEM5_BIN missing"; exit 2; }
+
+# --- primary outputs (data) + mirrors (repo) ---
 OUT_DATA="$DATA/SmartEdgeAI/results"
 LOG_DATA="$DATA/SmartEdgeAI/logs"
 OUT_IOT="$IOT/results"
 LOG_IOT="$IOT/logs"
-
-# ensure directories
 mkdir -p "$OUT_DATA" "$LOG_DATA" "$OUT_IOT" "$LOG_IOT"
 
 # export for child scripts
-export ROOT IOT DATA RUN CFG GEM5 OUT_DATA LOG_DATA OUT_IOT LOG_IOT
+export ROOT SRC IOT DATA RUN CFG GEM5_BIN OUT_DATA LOG_DATA OUT_IOT LOG_IOT
 
 # minimal env log
 {
   echo "==== env ===="
   echo "ROOT=$ROOT"
-  echo "GEM5=$GEM5"
+  echo "SRC=$SRC"
+  echo "GEM5_BIN=$GEM5_BIN"
   echo "CFG=$CFG"
   echo "RUN=$RUN"
   echo "OUT_DATA=$OUT_DATA"
@@ -45,4 +44,3 @@ export ROOT IOT DATA RUN CFG GEM5 OUT_DATA LOG_DATA OUT_IOT LOG_IOT
 } >> "$LOG_IOT/env.txt"
 
 echo "[env] READY"
-
diff --git a/scripts/10_run_one.sh b/scripts/10_run_one.sh
index 1932caf..4077aab 100755
--- a/scripts/10_run_one.sh
+++ b/scripts/10_run_one.sh
@@ -14,7 +14,7 @@ OUTDIR="$OUT_DATA/$TAG"
 mkdir -p "$OUTDIR"
 echo "[run_one] $TAG mem=$MEM -> $OUTDIR"
 
-"$GEM5" "$CFG" \
+"$GEM5_BIN" "$CFG" \
   --cmd="$RUN/$W" \
   --mem="$MEM" \
   --dvfs="$DV" \
@@ -24,7 +24,7 @@ echo "[run_one] $TAG mem=$MEM -> $OUTDIR"
   > "$LOG_DATA/${TAG}.stdout.log" \
   2> "$LOG_DATA/${TAG}.stderr.log"
 
-# mirror to repo (iot/)
+# mirror to repo
 rsync -a --delete "$OUTDIR/" "$OUT_IOT/$TAG/"
 rsync -a "$LOG_DATA/${TAG}."* "$LOG_IOT/" 2>/dev/null || true