[difftest] draft vcs linking

Failed to link due to snps doesn't implement the IEEE 1800-2023:
= note: /nix/store/2p1sq1nr09xr3xb1a9lrjgdanvk1aakb-binutils-2.42/bin/ld: warning: type of symbol `cosim_init' changed from 1 to 2 in /home/sequencer/t1/difftest/target/debug/deps/libonline_dpi-e08daffbb814a8db.rlib(online_dpi-e08daffbb814a8db.4twjnztmhnh46d6z.rcgu.o)
/nix/store/2p1sq1nr09xr3xb1a9lrjgdanvk1aakb-binutils-2.42/bin/ld: /home/sequencer/t1/difftest/target/debug/deps/libonline_dpi-e08daffbb814a8db.rlib(online_dpi-e08daffbb814a8db.3wnd5deuga8hai4e.rcgu.o): in function `online_dpi::svdpi::get_time':
/home/sequencer/t1/difftest/online_dpi/src/svdpi.rs:9:(.text._ZN10online_dpi5svdpi8get_time17hc271602d89503b28E+0x56): undefined reference to `svGetTime'
collect2: error: ld returned 1 exit status
= note: some `extern` functions couldn't be found; some native libraries may need to be installed or have their path specified
= note: use the `-l` flag to specify native libraries to link
= note: use the `cargo:rustc-link-lib` directive to specify the native libraries to link with Cargo (see https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-link-lib)

cosim_init is conflict with SNPS symbol, we need to change ours

Reproduce via:
- nix develop --impure  .#t1.blastoise.ip.vcs-emu
- cd difftest/
- cargo run --bin online_vcs -- --elf-file $(nix build --no-link --print-out-paths .#t1.blastoise.cases.intrinsic.softmax)/bin/* --timeout 10000 --log-level trace

difftest/online_vcs/build.rs

@@ -1,3 +1,13 @@
+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-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");
 }

difftest/online_vcs/src/main.rs

@@ -2,7 +2,7 @@
 extern crate online_dpi;
 
 use std::{
-  ffi::{c_char, c_int, CString},
+  ffi::{c_char, c_int, c_void, CString},
   ptr,
 };
 
@@ -15,5 +15,16 @@ fn main() {
   let argc = c_args.len() as c_int;
   let argv = c_args_ptr.as_ptr() as *mut *mut c_char;
 
-  // TODO
+  unsafe {
+    vcs_main(argc, argv);
+    VcsInit();
+    VcsSimUntilInterrupt();
+  }
 }
+
+extern "C" {
+  fn vcs_main(argc: c_int, argv: *mut *mut c_char) -> c_int;
+  fn VcsInit() -> c_void;
+  fn VcsSimUntilInterrupt() -> c_void;
+}
+

difftest/vcs-emu.nix

@@ -0,0 +1,68 @@
+{ 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" ];
+
+    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

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);

nix/t1/default.nix

@@ -117,8 +117,8 @@ lib.makeScope newScope
           };
           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/default.nix { verilated = vcs-emu-compiled; };
-          vcs-emu-trace = innerSelf.callPackage ../../difftest/default.nix { verilated = vcs-emu-compiled-trace; };
+          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 {