diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index eaa9321b4d..94a3f19cc2 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -42,7 +42,7 @@ jobs:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: "Build verilator emulator"
         run: |
-          nix build '.#t1.${{ matrix.config }}.ip.difftest' -L --no-link --cores 64
+          nix build '.#t1.${{ matrix.config }}.ip.verilator-emu' -L --no-link --cores 64
       - name: "Build all testcases"
         run: |
           # Build testcases with vlen 1024 and vlen 4096
@@ -81,7 +81,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: "Build verilator emulator with trace"
-        run: nix build '.#t1.${{ matrix.config }}.ip.difftest-trace' -L --no-link --cores 64
+        run: nix build '.#t1.${{ matrix.config }}.ip.verilator-emu-trace' -L --no-link --cores 64
 
   test-emit:
     if: '! github.event.pull_request.draft'
diff --git a/difftest/Cargo.toml b/difftest/Cargo.toml
index 00abdf691b..b4488928c7 100644
--- a/difftest/Cargo.toml
+++ b/difftest/Cargo.toml
@@ -6,6 +6,7 @@ members = [
     "offline",
     "online_dpi",
     "online_drive",
+    "online_vcs",
 ]
 exclude = [
     "spike_interfaces"
diff --git a/difftest/default.nix b/difftest/default.nix
index 8b3626cbaa..efcd77d71e 100644
--- a/difftest/default.nix
+++ b/difftest/default.nix
@@ -26,6 +26,7 @@ let
         ./offline
         ./online_dpi
         ./online_drive
+        ./online_vcs
         ./test_common
         ./Cargo.lock
         ./Cargo.toml
@@ -43,6 +44,7 @@ let
     ];
 
     buildFeatures = lib.optionals verilated.enable-trace [ "trace" ];
+    buildAndTestSubdir = "./online_drive";
 
     env = {
       VERILATED_INC_DIR = "${verilated}/include";
diff --git a/difftest/online_vcs/Cargo.toml b/difftest/online_vcs/Cargo.toml
new file mode 100644
index 0000000000..ff32311b7e
--- /dev/null
+++ b/difftest/online_vcs/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "online_vcs"
+edition = "2021"
+version.workspace = true
+
+[dependencies]
+online_dpi = { path = "../online_dpi", features = ["svvpi"] }
+
+[features]
+trace = ["online_dpi/trace"]
diff --git a/difftest/online_vcs/build.rs b/difftest/online_vcs/build.rs
new file mode 100644
index 0000000000..1144bac367
--- /dev/null
+++ b/difftest/online_vcs/build.rs
@@ -0,0 +1,14 @@
+use std::path::Path;
+use std::env;
+
+fn main() {
+  let vcs_lib_dir = env::var("VCS_LIB_DIR").unwrap();
+  println!("cargo:rustc-link-search=native={}", Path::new(&vcs_lib_dir).display());
+  let vcs_compiled_lib_dir = env::var("VCS_COMPILED_LIB_DIR").unwrap();
+  println!("cargo:rustc-env=LD_LIBRARY_PATH={}", Path::new(&vcs_lib_dir).display());
+  println!("cargo:rustc-link-search=native={}", Path::new(&vcs_compiled_lib_dir).display());
+  println!("cargo::rustc-link-lib=TestBench");
+  println!("cargo::rustc-link-lib=vcsnew64");
+  println!("cargo::rustc-link-lib=vcs_tls");
+  println!("cargo::rustc-link-lib=vfs");
+}
diff --git a/difftest/online_vcs/src/main.rs b/difftest/online_vcs/src/main.rs
new file mode 100644
index 0000000000..00c7fbde88
--- /dev/null
+++ b/difftest/online_vcs/src/main.rs
@@ -0,0 +1,30 @@
+// force link with online_dpi
+extern crate online_dpi;
+
+use std::{
+  ffi::{c_char, c_int, c_void, CString},
+  ptr,
+};
+
+fn main() {
+  let c_args: Vec<CString> = std::env::args().map(|arg| CString::new(arg).unwrap()).collect();
+
+  let mut c_args_ptr: Vec<*const c_char> = c_args.iter().map(|arg| arg.as_ptr()).collect();
+  c_args_ptr.push(ptr::null());
+
+  let argc = c_args.len() as c_int;
+  let argv = c_args_ptr.as_ptr() as *mut *mut c_char;
+
+  unsafe {
+    vcs_main(argc, argv);
+    VcsInit();
+    VcsSimUntil(1<<31);
+  }
+}
+
+extern "C" {
+  fn vcs_main(argc: c_int, argv: *mut *mut c_char) -> c_int;
+  fn VcsInit() -> c_void;
+  fn VcsSimUntil(c: c_int) -> c_void;
+}
+
diff --git a/difftest/vcs-emu.nix b/difftest/vcs-emu.nix
new file mode 100644
index 0000000000..4da9c46490
--- /dev/null
+++ b/difftest/vcs-emu.nix
@@ -0,0 +1,69 @@
+{ lib
+, callPackage
+, elaborateConfig
+
+, rustPlatform
+
+, rust-analyzer
+, rust-bindgen
+
+, vcStaticInstallPath
+, vcs-lib
+
+, cmake
+, clang-tools
+}:
+
+let
+  spike_interfaces = callPackage ./spike_interfaces { };
+
+  self = rustPlatform.buildRustPackage {
+    name = "t1-vcs-emu";
+    src = with lib.fileset; toSource {
+      root = ./.;
+      fileset = unions [
+        ./spike_rs
+        ./offline
+        ./online_dpi
+        ./online_drive
+        ./online_vcs
+        ./test_common
+        ./Cargo.lock
+        ./Cargo.toml
+      ];
+    };
+
+    buildInputs = [
+      spike_interfaces
+      vcs-lib
+    ];
+
+    buildFeatures = lib.optionals vcs-lib.enable-trace [ "trace" ];
+    buildAndTestSubdir = "./online_vcs";
+
+    env = {
+      VCS_LIB_DIR = "${vcStaticInstallPath}/vcs-mx/linux64/lib";
+      VCS_COMPILED_LIB_DIR = "${vcs-lib}/lib";
+      DESIGN_VLEN = elaborateConfig.parameter.vLen;
+      DESIGN_DLEN = elaborateConfig.parameter.dLen;
+    };
+
+    cargoLock = {
+      lockFile = ./Cargo.lock;
+    };
+
+    dontUseCmakeConfigure = true;
+
+    passthru = {
+      devShell = self.overrideAttrs (old: {
+        nativeBuildInputs = old.nativeBuildInputs ++ [
+          rust-analyzer
+          rust-bindgen
+          clang-tools
+        ];
+      });
+      inherit spike_interfaces;
+    };
+  };
+in
+self
diff --git a/ipemu/src/TestBench.scala b/ipemu/src/TestBench.scala
index 3e23afc8ce..9d24b3f8c5 100644
--- a/ipemu/src/TestBench.scala
+++ b/ipemu/src/TestBench.scala
@@ -37,11 +37,6 @@ class TestBench(generator: SerializableModuleGenerator[T1, T1Parameter]) extends
          |  export "DPI-C" function dump_wave;
          |  function dump_wave(input string file);
          |`ifdef VCS
-         |    $$fsdbDumpfile(file);
-         |    $$fsdbDumpvars("+all");
-         |    $$fsdbDumpSVA();
-         |    $$fsdbDumpvars(0);
-         |    $$fsdbDumpon;
          |`endif
          |`ifdef VERILATOR
          |    $$dumpfile(file);
diff --git a/nix/overlay.nix b/nix/overlay.nix
index 4dae99039a..c6027ba316 100644
--- a/nix/overlay.nix
+++ b/nix/overlay.nix
@@ -23,6 +23,11 @@ rec {
   circt-full = final.callPackage ./pkgs/circt-full.nix { };
   rvv-codegen = final.callPackage ./pkgs/rvv-codegen.nix { };
   add-determinism = final.callPackage ./pkgs/add-determinism { }; # faster strip-undetereminism
+  # Using VCS need to set VC_STATIC_HOME and SNPSLMD_LICENSE_FILE to impure env, and add sandbox dir to VC_STATIC_HOME
+  vcs-fhs-env = final.callPackage ./pkgs/vcs-fhs-env.nix {
+    vcStaticInstallPath = builtins.getEnv "VC_STATIC_HOME";
+    snpsLicenseFile = builtins.getEnv "SNPSLMD_LICENSE_FILE";
+  };
 
   mill = let jre = final.jdk21; in
     (prev.mill.override { inherit jre; }).overrideAttrs (_: {
diff --git a/nix/pkgs/vcs-fhs-env.nix b/nix/pkgs/vcs-fhs-env.nix
new file mode 100644
index 0000000000..37baa934d9
--- /dev/null
+++ b/nix/pkgs/vcs-fhs-env.nix
@@ -0,0 +1,87 @@
+{ buildFHSEnv
+  # e.g. /opt/synopsys/vc_static/V-2023.12
+, vcStaticInstallPath
+  # e.g. port@addr
+, snpsLicenseFile
+}:
+buildFHSEnv {
+  name = "vcs-fhs-env";
+  profile = ''
+    export TCL_TZ=UTC
+    export VC_STATIC_HOME=${vcStaticInstallPath}
+    export VCS_HOME=${vcStaticInstallPath}/vcs-mx
+    export VCS_TARGET_ARCH=amd64
+    export VCS_ARCH_OVERRIDE=linux
+    export VERDI_HOME=${vcStaticInstallPath}/verdi
+    export NOVAS_HOME=${vcStaticInstallPath}/verdi
+    export SPYGLASS_HOME=${vcStaticInstallPath}/SG_COMPAT/SPYGLASS_HOME
+    export SNPS_VERDI_CBUG_LCA=1
+    export SNPSLMD_LICENSE_FILE=${snpsLicenseFile}
+
+    export PATH=${vcStaticInstallPath}/bin:$PATH
+    export PATH=${vcStaticInstallPath}/verdi/bin:$PATH
+    export PATH=${vcStaticInstallPath}/vcs-mx/bin:$PATH
+    export PATH=${vcStaticInstallPath}/SG_COMPAT/SPYGLASS_HOME/bin:$PATH
+
+    export LD_LIBRARY_PATH=/usr/lib64/
+    export LD_LIBRARY_PATH=${vcStaticInstallPath}/verdi/share/PLI/lib/LINUX64:$LD_LIBRARY_PATH
+    export LD_LIBRARY_PATH=${vcStaticInstallPath}/verdi/share/NPI/lib/LINUX64:$LD_LIBRARY_PATH
+  '';
+  targetPkgs = (ps: with ps; [
+    libGL
+    util-linux
+    libxcrypt-legacy
+    coreutils-full
+    ncurses5
+    gmp5
+    bzip2
+    glib
+    bc
+    time
+    elfutils
+    ncurses5
+    e2fsprogs
+    cyrus_sasl
+    expat
+    sqlite
+    (nssmdns.overrideAttrs rec {
+      version = "0.14.1";
+      src = fetchFromGitHub {
+        owner = "avahi";
+        repo = "nss-mdns";
+        rev = "v${version}";
+        hash = "sha256-7RqV0hyfcZ168QfeHVtCJpyP4pI6cMeekJ2hDHNurdA=";
+      };
+    })
+    (libkrb5.overrideAttrs rec {
+      version = "1.18.2";
+      src = fetchurl {
+        url = "https://kerberos.org/dist/krb5/${lib.versions.majorMinor version}/krb5-${version}.tar.gz";
+        hash = "sha256-xuTJ7BqYFBw/XWbd8aE1VJBQyfq06aRiDumyIIWHOuA=";
+      };
+      sourceRoot = "krb5-${version}/src";
+    })
+    (gnugrep.overrideAttrs rec {
+      version = "3.1";
+      doCheck = false;
+      src = fetchurl {
+        url = "mirror://gnu/grep/grep-${version}.tar.xz";
+        hash = "sha256-22JcerO7PudXs5JqXPqNnhw5ka0kcHqD3eil7yv3oH4=";
+      };
+    })
+    keyutils
+    graphite2
+    libpulseaudio
+    gcc
+    gnumake
+    xorg.libX11
+    xorg.libXft
+    xorg.libXScrnSaver
+    xorg.libXext
+    xorg.libxcb
+    xorg.libXau
+    xorg.libXrender
+    xorg.libXcomposite
+    xorg.libXi
+  ]);
+}
diff --git a/nix/t1/default.nix b/nix/t1/default.nix
index 1e12d07d5a..e67333b59c 100644
--- a/nix/t1/default.nix
+++ b/nix/t1/default.nix
@@ -62,27 +62,63 @@ lib.makeScope newScope
         ip = rec {
           recurseForDerivations = true;
 
-          elaborate = innerSelf.callPackage ./elaborate.nix { target = "ip"; /* use-binder = true; */ };
+          # T1 RTL.
+          elaborate = innerSelf.callPackage ./elaborate.nix { target = "ip"; };
           mlirbc = innerSelf.callPackage ./mlirbc.nix { inherit elaborate; };
-          rtl = innerSelf.callPackage ./rtl.nix { inherit mlirbc; };
-
+          rtl = innerSelf.callPackage ./rtl.nix {
+            inherit mlirbc;
+            mfcArgs = lib.escapeShellArgs [
+              "-O=release"
+              "--disable-all-randomization"
+              "--split-verilog"
+              "--preserve-values=all"
+              "--strip-debug-info"
+              "--strip-fir-debug-info"
+              "--verification-flavor=sva"
+              "--lowering-options=verifLabels,omitVersionComment,emittedLineLength=240,locationInfoStyle=none"
+            ];
+          };
           omreader = self.omreader-unwrapped.mkWrapper { inherit mlirbc; };
-
           om = innerSelf.callPackage ./om.nix { inherit mlirbc; };
 
-          emu-elaborate = innerSelf.callPackage ./elaborate.nix { target = "ipemu"; /* use-binder = true; */ };
+          emu-elaborate = innerSelf.callPackage ./elaborate.nix { target = "ipemu"; };
           emu-mlirbc = innerSelf.callPackage ./mlirbc.nix { elaborate = emu-elaborate; };
-          emu-omreader = self.omreader-unwrapped.mkWrapper { mlirbc = emu-mlirbc; };
-          emu-rtl = innerSelf.callPackage ./rtl.nix { mlirbc = emu-mlirbc; };
-
-          verilated = innerSelf.callPackage ./verilated.nix { rtl = emu-rtl; };
-          verilated-trace = innerSelf.callPackage ./verilated.nix { rtl = emu-rtl; enable-trace = true; };
-
-          emu = innerSelf.callPackage ./ipemu.nix { rtl = ip.emu-rtl; stdenv = moldStdenv; };
-          emu-trace = innerSelf.callPackage ./ipemu.nix { rtl = emu-rtl; stdenv = moldStdenv; do-trace = true; };
 
-          difftest = innerSelf.callPackage ../../difftest/default.nix { inherit verilated; };
-          difftest-trace = innerSelf.callPackage ../../difftest/default.nix { verilated = verilated-trace; };
+          # T1 Verilator Emulator
+          verilator-emu-omreader = self.omreader-unwrapped.mkWrapper { mlirbc = emu-mlirbc; };
+          verilator-emu-rtl = innerSelf.callPackage ./rtl.nix {
+            mlirbc = emu-mlirbc;
+            mfcArgs = lib.escapeShellArgs [
+              "-O=release"
+              "--split-verilog"
+              "--preserve-values=all"
+              "--verification-flavor=if-else-fatal"
+              "--lowering-options=verifLabels,omitVersionComment"
+              "--strip-debug-info"
+            ];
+          };
+          verilator-emu-rtl-verilated = innerSelf.callPackage ./verilated.nix { rtl = verilator-emu-rtl; stdenv = moldStdenv; };
+          verilator-emu-rtl-verilated-trace = innerSelf.callPackage ./verilated.nix { rtl = verilator-emu-rtl; stdenv = moldStdenv; enable-trace = true; };
+          verilator-emu = innerSelf.callPackage ../../difftest/default.nix { verilated = verilator-emu-rtl-verilated; };
+          verilator-emu-trace = innerSelf.callPackage ../../difftest/default.nix { verilated = verilator-emu-rtl-verilated-trace; };
+
+          # T1 VCS Emulator
+          vcs-emu-omreader = self.omreader-unwrapped.mkWrapper { mlirbc = emu-mlirbc; };
+          vcs-emu-rtl = innerSelf.callPackage ./rtl.nix {
+            mlirbc = emu-mlirbc;
+            mfcArgs = lib.escapeShellArgs [
+              "-O=release"
+              "--split-verilog"
+              "--preserve-values=all"
+              "--verification-flavor=sva"
+              "--lowering-options=verifLabels,omitVersionComment"
+              "--strip-debug-info"
+            ];
+          };
+          vcs-emu-compiled = innerSelf.callPackage ./vcs.nix { rtl = vcs-emu-rtl; };
+          vcs-emu-compiled-trace = innerSelf.callPackage ./vcs.nix { rtl = vcs-emu-rtl; enable-trace = true; };
+          vcs-emu = innerSelf.callPackage ../../difftest/vcs-emu.nix { vcs-lib = vcs-emu-compiled; vcStaticInstallPath = builtins.getEnv "VC_STATIC_HOME"; };
+          vcs-emu-trace = innerSelf.callPackage ../../difftest/vcs-emu.nix { vcs-lib = vcs-emu-compiled-trace; vcStaticInstallPath = builtins.getEnv "VC_STATIC_HOME"; };
         };
 
         subsystem = rec {
diff --git a/nix/t1/elaborate.nix b/nix/t1/elaborate.nix
index 691a701cd3..a531ac1dff 100644
--- a/nix/t1/elaborate.nix
+++ b/nix/t1/elaborate.nix
@@ -12,7 +12,7 @@
 }:
 
 assert lib.assertMsg
-  (lib.elem target [ "ip" "ipemu" "subsystem" "subsystememu" ])
+  (lib.elem target [ "ip" "ipemu" ])
   "Unknown elaborate target ${target}";
 
 let
diff --git a/nix/t1/ipemu.nix b/nix/t1/ipemu.nix
deleted file mode 100644
index 2002af62f1..0000000000
--- a/nix/t1/ipemu.nix
+++ /dev/null
@@ -1,53 +0,0 @@
-{ stdenv
-, lib
-
-  # emulator deps
-, cmake
-, libargs
-, spdlog
-, fmt
-, libspike
-, dramsim3
-, nlohmann_json
-, ninja
-, verilator
-, zlib
-
-, rtl
-
-, do-trace ? false
-}:
-
-stdenv.mkDerivation {
-  name = "t1-${rtl.elaborateConfig}-ipemu" + lib.optionalString do-trace "-trace";
-
-  src = ../../ipemu/csrc;
-
-  # CMakeLists.txt will read the environment
-  env.VERILATE_SRC_DIR = toString rtl;
-
-  cmakeFlags = lib.optionals do-trace [
-    "-DVERILATE_TRACE=ON"
-  ];
-
-  nativeBuildInputs = [
-    cmake
-    verilator
-    ninja
-  ];
-
-  buildInputs = [
-    zlib
-    libargs
-    spdlog
-    fmt
-    libspike
-    dramsim3
-    nlohmann_json
-  ];
-
-  meta = {
-    mainProgram = "emulator";
-    description = "IP emulator for config ${rtl.elaborateConfig}";
-  };
-}
diff --git a/nix/t1/rtl.nix b/nix/t1/rtl.nix
index 9f3beed965..5b9d43369d 100644
--- a/nix/t1/rtl.nix
+++ b/nix/t1/rtl.nix
@@ -1,19 +1,12 @@
 { stdenvNoCC
 , lib
-
+, mfcArgs
 , circt
 , mlirbc
 }:
 
 let
-  mfcArgs = lib.escapeShellArgs [
-    "-O=debug"
-    "--split-verilog"
-    "--preserve-values=named"
-    "--lowering-options=verifLabels,omitVersionComment"
-    "--strip-debug-info"
-  ];
-  fixupFilelist = lib.elem mlirbc.elaborateTarget [ "ipemu" "subsystememu" ];
+  fixupFilelist = lib.elem mlirbc.elaborateTarget [ "ipemu" ];
 in
 stdenvNoCC.mkDerivation {
   name = "t1-${mlirbc.elaborateConfig}-${mlirbc.elaborateTarget}-rtl";
diff --git a/nix/t1/vcs.nix b/nix/t1/vcs.nix
new file mode 100644
index 0000000000..06fb282105
--- /dev/null
+++ b/nix/t1/vcs.nix
@@ -0,0 +1,55 @@
+{ lib
+, stdenv
+, configName
+, rtl
+, vcs-fhs-env
+, enable-trace ? false
+}:
+stdenv.mkDerivation {
+  name = "${configName}-vcs";
+
+  # require license
+  __noChroot = true;
+
+  src = rtl;
+
+  nativeBuildInputs = [ vcs-fhs-env ];
+
+  buildPhase = ''
+    runHook preBuild
+
+    echo "[nix] running VCS"
+    ${vcs-fhs-env}/bin/vcs-fhs-env vcs \
+      -sverilog \
+      -full64 \
+      -slave \
+      -e vcs_main \
+      -file filelist.f \
+      -timescale=1ns/1ps \
+      ${lib.optionalString enable-trace "--trace-fst"} \
+      ${lib.optionalString enable-trace "-P $VERDI_HOME/share/PLI/VCS/LINUX64/novas.tab $VERDI_HOME/share/PLI/VCS/LINUX64/pli.a"} \
+      ${lib.optionalString enable-trace "-debug_access+pp+dmptf+thread"} \
+      ${lib.optionalString enable-trace "-kdb=common_elab,hgldd_all"} \
+      -o libTestBench.so
+
+    runHook postBuild
+  '';
+
+  passthru = {
+    inherit enable-trace;
+  };
+
+  installPhase = ''
+    runHook preInstall
+
+    mkdir -p $out/ $out/lib
+    cp libTestBench.so $out/lib
+    cp *.so $out/lib
+
+    # backup daidir
+    mkdir -p $out/share/daidir
+    cp -r libTestBench.so.daidir/*  $out/share/daidir
+
+    runHook postInstall
+  '';
+}
diff --git a/tests/default.nix b/tests/default.nix
index d84a1effed..009a9be32a 100644
--- a/tests/default.nix
+++ b/tests/default.nix
@@ -4,8 +4,8 @@
 , newScope
 , rv32-stdenv
 , runCommand
-, difftest
-, difftest-trace
+, verilator-emu
+, verilator-emu-trace
 }:
 
 let
@@ -20,7 +20,7 @@ let
   scope = lib.recurseIntoAttrs (lib.makeScope newScope (casesSelf: {
     recurseForDerivations = true;
 
-    inherit difftest difftest-trace;
+    inherit verilator-emu verilator-emu-trace;
 
     makeEmuResult = casesSelf.callPackage ./make-emu-result.nix { };
 
diff --git a/tests/make-emu-result.nix b/tests/make-emu-result.nix
index f31553f4fd..129de6c0fa 100644
--- a/tests/make-emu-result.nix
+++ b/tests/make-emu-result.nix
@@ -3,8 +3,8 @@
 , stdenvNoCC
 , jq
 , zstd
-, difftest
-, difftest-trace
+, verilator-emu
+, verilator-emu-trace
 , elaborateConfigJson
 }:
 
@@ -19,7 +19,7 @@ let
 
     dontUnpack = true;
 
-    difftestDriver = "${difftest}/bin/online_drive";
+    difftestDriver = "${verilator-emu}/bin/online_drive";
     difftestArgs = [
       "--elf-file"
       "${testCase}/bin/${testCase.pname}.elf"
@@ -76,7 +76,7 @@ let
     '';
 
     passthru.with-trace = self.overrideAttrs (old: {
-      difftestDriver = "${difftest-trace}/bin/online_drive";
+      difftestDriver = "${verilator-emu-trace}/bin/online_drive";
       difftestArgs = old.difftestArgs ++ [ "--wave-path" "${placeholder "out"}/wave.fst" ];
       postCheck = ''
         if [ ! -r "$out/wave.fst" ]; then
@@ -89,7 +89,7 @@ let
     passthru.with-offline = self.overrideAttrs (old: {
       preInstall = ''
         set +e
-        "${difftest}/bin/offline" \
+        "${verilator-emu}/bin/offline" \
           --elf-file ${testCase}/bin/${testCase.pname}.elf \
           --log-file $out/rtl-event.jsonl \
           --log-level ERROR &> $out/offline-check-journal