feat: implement privileged mode support

sim/scripts/run_opensbi.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+set -u
+
+TESTBENCH="../verilator/obj_dir/VCore"
+OPENSBI_BIN="${OPENSBI_BIN:-../../opensbi/build/platform/generic/firmware/fw_payload.elf}"
+TIMEOUT_SECONDS="${TIMEOUT_SECONDS:-10}"
+
+if [ ! -x "$TESTBENCH" ]; then
+    echo "Error: Testbench not found. Run 'make -C sim/verilator compile' first."
+    exit 1
+fi
+
+if [ ! -f "$OPENSBI_BIN" ]; then
+    echo "Error: OpenSBI payload not found: $OPENSBI_BIN"
+    echo "Set OPENSBI_BIN to a firmware ELF path."
+    exit 2
+fi
+
+echo "Running OpenSBI payload: $OPENSBI_BIN"
+timeout "${TIMEOUT_SECONDS}s" "$TESTBENCH" "$OPENSBI_BIN"
+exitcode=$?
+
+if [ "$exitcode" -eq 124 ]; then
+    echo "OpenSBI run timed out"
+    exit 124
+fi
+
+exit "$exitcode"