[Linux] Add cvars to enable mangohud and gamemode

src/xenia/app/emulator_window.cc

@@ -200,6 +200,18 @@ DEFINE_int32(recent_titles_entry_amount, 10,
              "Allows user to define how many titles is saved in list of "
              "recently played titles.",
              "General");
+
+#if XE_PLATFORM_LINUX
+DEFINE_bool(
+    use_mangohud, false,
+    "Enable MangoHUD overlay when launching games in separate processes.\n"
+    "MangoHUD must be installed on your system for this to work.",
+    "Linux");
+DEFINE_bool(use_gamemode, false,
+            "Use Feral GameMode when launching games in separate processes.\n"
+            "GameMode must be installed on your system for this to work.",
+            "Linux");
+#endif
 namespace xe {
 namespace app {
 
@@ -2238,8 +2250,23 @@ void EmulatorWindow::LaunchTitleInNewProcess(
 
   if (pid == 0) {
     // Child process
+
+    // Set MangoHUD environment variable if enabled
+    if (cvars::use_mangohud) {
+      setenv("MANGOHUD", "1", 1);
+    }
+
     std::vector<const char*> argv;
-    argv.push_back(executable_path.c_str());
+    std::string gamemode_cmd;
+
+    // If GameMode is enabled, use gamemoderun as the executable
+    if (cvars::use_gamemode) {
+      gamemode_cmd = "gamemoderun";
+      argv.push_back(gamemode_cmd.c_str());
+      argv.push_back(executable_path.c_str());
+    } else {
+      argv.push_back(executable_path.c_str());
+    }
 
     // Pass the config file if one is being used
     std::string config_arg;
@@ -2270,10 +2297,16 @@ void EmulatorWindow::LaunchTitleInNewProcess(
     argv.push_back(nullptr);
 
     // Execute the new process
-    execv(executable_path.c_str(), const_cast<char**>(argv.data()));
+    if (cvars::use_gamemode) {
+      // Use execvp to search PATH for gamemoderun
+      execvp(gamemode_cmd.c_str(), const_cast<char**>(argv.data()));
+    } else {
+      execv(executable_path.c_str(), const_cast<char**>(argv.data()));
+    }
 
-    // If execv returns, it failed
-    XELOGE("Failed to execute: {}", executable_path.string());
+    // If exec returns, it failed
+    XELOGE("Failed to execute: {}",
+           cvars::use_gamemode ? gamemode_cmd : executable_path.string());
     std::exit(1);
   } else if (pid < 0) {
     // Fork failed

src/xenia/ui/config_dialog_qt.cc

@@ -29,6 +29,10 @@
 #include "xenia/config.h"
 #include "xenia/ui/config_helpers.h"
 
+#if XE_PLATFORM_LINUX
+#include <unistd.h>
+#endif
+
 namespace xe {
 namespace app {
 
@@ -37,6 +41,28 @@ namespace {
 // Use the shared enum options from config_helpers.h
 using xe::ui::GetKnownEnumOptions;
 
+#if XE_PLATFORM_LINUX
+// Check if a command exists in PATH by searching each directory
+bool IsCommandAvailable(const std::string& command) {
+  std::string path_env = std::getenv("PATH") ? std::getenv("PATH") : "";
+  if (path_env.empty()) {
+    return false;
+  }
+
+  // Split PATH by ':'
+  std::istringstream path_stream(path_env);
+  std::string path_dir;
+  while (std::getline(path_stream, path_dir, ':')) {
+    std::filesystem::path full_path = std::filesystem::path(path_dir) / command;
+    if (std::filesystem::exists(full_path) &&
+        access(full_path.c_str(), X_OK) == 0) {
+      return true;
+    }
+  }
+  return false;
+}
+#endif
+
 }  // namespace
 
 ConfigDialogQt::ConfigDialogQt(QWidget* parent, EmulatorWindow* emulator_window)
@@ -246,6 +272,23 @@ QWidget* ConfigDialogQt::CreateEditorWidget(ConfigVarInfo* var_info) {
     checkbox->setChecked(var_info->pending_value == "true");
     connect(checkbox, &QCheckBox::checkStateChanged, this,
             &ConfigDialogQt::OnValueChanged);
+
+#if XE_PLATFORM_LINUX
+    // Disable Linux-specific options if the required tools aren't installed
+    if (var_info->name == "use_mangohud" && !IsCommandAvailable("mangohud")) {
+      checkbox->setEnabled(false);
+      checkbox->setToolTip(
+          "MangoHUD is not installed or not found in PATH. Install MangoHUD "
+          "to use this feature.");
+    } else if (var_info->name == "use_gamemode" &&
+               !IsCommandAvailable("gamemoderun")) {
+      checkbox->setEnabled(false);
+      checkbox->setToolTip(
+          "GameMode is not installed or not found in PATH. Install GameMode "
+          "to use this feature.");
+    }
+#endif
+
     return checkbox;
   } else if (enum_it != enum_options.end()) {
     // Dropdown for enum-like cvars