From 2f653746942117e7940f8a708a3c65f90a7a83b8 Mon Sep 17 00:00:00 2001
From: Putta Khunchalee <ultimaweapon@outlook.com>
Date: Sat, 23 Nov 2024 20:00:30 +0700
Subject: [PATCH] Merges VMM screen into graphics module (#1134)

---
 gui/core.h                                    | 11 ----
 gui/core.hpp                                  |  9 ---
 gui/main_window.cpp                           | 43 -------------
 gui/main_window.hpp                           |  2 -
 gui/src/{screen => graphics}/metal/buffer.rs  |  2 +-
 gui/src/graphics/metal/mod.rs                 | 21 +++++--
 .../metal/mod.rs => graphics/metal/screen.rs} |  6 +-
 gui/src/graphics/mod.rs                       | 10 +--
 gui/src/{screen => graphics}/vulkan/buffer.rs |  2 +-
 gui/src/graphics/vulkan/mod.rs                | 61 +++++++++++--------
 .../mod.rs => graphics/vulkan/screen.rs}      |  6 +-
 gui/src/lib.rs                                |  1 -
 gui/src/main.rs                               | 59 ++++++++----------
 gui/src/screen/mod.rs                         | 16 -----
 gui/src/vmm/ffi.rs                            | 17 ------
 gui/src/vmm/mod.rs                            | 24 +++-----
 16 files changed, 95 insertions(+), 195 deletions(-)
 rename gui/src/{screen => graphics}/metal/buffer.rs (83%)
 rename gui/src/{screen/metal/mod.rs => graphics/metal/screen.rs} (95%)
 rename gui/src/{screen => graphics}/vulkan/buffer.rs (83%)
 rename gui/src/{screen/vulkan/mod.rs => graphics/vulkan/screen.rs} (96%)
 delete mode 100644 gui/src/screen/mod.rs
 delete mode 100644 gui/src/vmm/ffi.rs

diff --git a/gui/core.h b/gui/core.h
index 691a25233..6113919c6 100644
--- a/gui/core.h
+++ b/gui/core.h
@@ -51,11 +51,6 @@ struct Profile;
  */
 struct RustError;
 
-/**
- * Manage a virtual machine that run the kernel.
- */
-struct Vmm;
-
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
@@ -130,12 +125,6 @@ struct RustError *update_firmware(const char *root,
                                   void *cx,
                                   void (*status)(const char*, uint64_t, uint64_t, void*));
 
-void vmm_free(struct Vmm *vmm);
-
-void vmm_shutdown(struct Vmm *vmm);
-
-bool vmm_shutting_down(struct Vmm *vmm);
-
 #ifdef __cplusplus
 }  // extern "C"
 #endif  // __cplusplus
diff --git a/gui/core.hpp b/gui/core.hpp
index debd951c7..160b72051 100644
--- a/gui/core.hpp
+++ b/gui/core.hpp
@@ -122,12 +122,3 @@ inline void Rust<RustError>::free()
         m_ptr = nullptr;
     }
 }
-
-template<>
-inline void Rust<Vmm>::free()
-{
-    if (m_ptr) {
-        vmm_free(m_ptr);
-        m_ptr = nullptr;
-    }
-}
diff --git a/gui/main_window.cpp b/gui/main_window.cpp
index c116176ad..3646c1acb 100644
--- a/gui/main_window.cpp
+++ b/gui/main_window.cpp
@@ -218,26 +218,6 @@ void MainWindow::closeEvent(QCloseEvent *event)
     // This will set to accept by QMainWindow::closeEvent.
     event->ignore();
 
-    // Ask user to confirm.
-    if (m_vmm) {
-        // Ask user to confirm only if we did not shutdown the VMM programmatically.
-        if (!vmm_shutting_down(m_vmm)) {
-            QMessageBox confirm(this);
-
-            confirm.setText("Do you want to exit?");
-            confirm.setInformativeText("The running game will be terminated.");
-            confirm.setStandardButtons(QMessageBox::Cancel | QMessageBox::Yes);
-            confirm.setDefaultButton(QMessageBox::Cancel);
-            confirm.setIcon(QMessageBox::Warning);
-
-            if (confirm.exec() != QMessageBox::Yes) {
-                return;
-            }
-        }
-
-        killVmm();
-    }
-
     // Save geometry.
     QSettings settings;
 
@@ -484,27 +464,6 @@ void MainWindow::startDebug(const QString &addr)
     }
 }
 
-bool MainWindow::requireVmmStopped()
-{
-    if (m_vmm) {
-        QMessageBox prompt(this);
-
-        prompt.setText("Action requires VMM to be stopped to continue.");
-        prompt.setInformativeText("Do you want to kill the VMM?");
-        prompt.setStandardButtons(QMessageBox::Cancel | QMessageBox::Yes);
-        prompt.setDefaultButton(QMessageBox::Cancel);
-        prompt.setIcon(QMessageBox::Warning);
-
-        if (prompt.exec() != QMessageBox::Yes) {
-            return false;
-        }
-
-        killVmm();
-    }
-
-    return true;
-}
-
 void MainWindow::stopDebug()
 {
     // We can't free the VMM here because the thread that trigger this method are waiting
@@ -525,8 +484,6 @@ void MainWindow::stopDebug()
 
 void MainWindow::killVmm()
 {
-    m_vmm.free();
-
     delete m_debugNoti;
     m_debugNoti = nullptr;
 }
diff --git a/gui/main_window.hpp b/gui/main_window.hpp
index ec1f0e11f..1d377d6b5 100644
--- a/gui/main_window.hpp
+++ b/gui/main_window.hpp
@@ -46,7 +46,6 @@ private slots:
     void vmmError(const QString &msg);
     void waitKernelExit(bool success);
     bool loadGame(const QString &gameId);
-    bool requireVmmStopped();
     void stopDebug();
     void killVmm();
 
@@ -58,7 +57,6 @@ private slots:
     Screen *m_screen;
     Rust<DebugServer> m_debugServer;
     QSocketNotifier *m_debugNoti;
-    Rust<Vmm> m_vmm; // Destroy first.
 };
 
 namespace Args {
diff --git a/gui/src/screen/metal/buffer.rs b/gui/src/graphics/metal/buffer.rs
similarity index 83%
rename from gui/src/screen/metal/buffer.rs
rename to gui/src/graphics/metal/buffer.rs
index af375c752..2fc55b1cc 100644
--- a/gui/src/screen/metal/buffer.rs
+++ b/gui/src/graphics/metal/buffer.rs
@@ -1,4 +1,4 @@
-use super::ScreenBuffer;
+use crate::graphics::ScreenBuffer;
 
 /// Manages Metal off-screen buffers.
 pub struct MetalBuffer {}
diff --git a/gui/src/graphics/metal/mod.rs b/gui/src/graphics/metal/mod.rs
index cccc5b45b..b8f313580 100644
--- a/gui/src/graphics/metal/mod.rs
+++ b/gui/src/graphics/metal/mod.rs
@@ -1,18 +1,23 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
+use self::screen::MetalScreen;
+use super::Graphics;
 use metal::Device;
 use std::ops::Deref;
 use thiserror::Error;
 
+mod buffer;
+mod screen;
+
 pub struct Metal {
     devices: Vec<metal::Device>,
 }
 
-impl super::GraphicsApi for Metal {
+impl Graphics for Metal {
+    type Err = MetalError;
     type PhysicalDevice = metal::Device;
+    type Screen = MetalScreen;
 
-    type CreateError = MetalCreateError;
-
-    fn new() -> Result<Self, Self::CreateError> {
+    fn new() -> Result<Self, Self::Err> {
         Ok(Self {
             devices: Device::all(),
         })
@@ -21,6 +26,10 @@ impl super::GraphicsApi for Metal {
     fn physical_devices(&self) -> &[Self::PhysicalDevice] {
         &self.devices
     }
+
+    fn create_screen(&mut self) -> Result<Self::Screen, Self::Err> {
+        todo!()
+    }
 }
 
 impl super::PhysicalDevice for metal::Device {
@@ -29,6 +38,6 @@ impl super::PhysicalDevice for metal::Device {
     }
 }
 
-/// Represents an error when [`Metal::new()`] fails.
+/// Implementation of [`Graphics::Err`] for Metal.
 #[derive(Debug, Error)]
-pub enum MetalCreateError {}
+pub enum MetalError {}
diff --git a/gui/src/screen/metal/mod.rs b/gui/src/graphics/metal/screen.rs
similarity index 95%
rename from gui/src/screen/metal/mod.rs
rename to gui/src/graphics/metal/screen.rs
index 7aae6e532..831eae1ac 100644
--- a/gui/src/screen/metal/mod.rs
+++ b/gui/src/graphics/metal/screen.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
-use self::buffer::MetalBuffer;
-use crate::graphics::{Screen, ScreenBuffer};
+use super::buffer::MetalBuffer;
+use crate::graphics::Screen;
 use crate::vmm::VmmScreen;
 use metal::{CAMetalLayer, Device, MetalLayer};
 use objc::runtime::{Object, NO, YES};
@@ -9,8 +9,6 @@ use std::ptr::null_mut;
 use std::sync::Arc;
 use thiserror::Error;
 
-mod buffer;
-
 /// Implementation of [`Screen`] using Metal.
 ///
 /// Fields in this struct need to be dropped in a correct order.
diff --git a/gui/src/graphics/mod.rs b/gui/src/graphics/mod.rs
index 1024658c1..0b8c08112 100644
--- a/gui/src/graphics/mod.rs
+++ b/gui/src/graphics/mod.rs
@@ -13,14 +13,14 @@ pub type DefaultApi = self::engine::Vulkan;
 pub type DefaultApi = self::engine::Metal;
 
 /// The underlying graphics engine (e.g. Vulkan).
-pub trait GraphicsApi: Sized + 'static {
+pub trait Graphics: Sized + 'static {
+    type Err: Error;
     type PhysicalDevice: PhysicalDevice;
+    type Screen: Screen;
 
-    type CreateError: core::error::Error;
-
-    fn new() -> Result<Self, Self::CreateError>;
-
+    fn new() -> Result<Self, Self::Err>;
     fn physical_devices(&self) -> &[Self::PhysicalDevice];
+    fn create_screen(&mut self) -> Result<Self::Screen, Self::Err>;
 }
 
 pub trait PhysicalDevice: Sized {
diff --git a/gui/src/screen/vulkan/buffer.rs b/gui/src/graphics/vulkan/buffer.rs
similarity index 83%
rename from gui/src/screen/vulkan/buffer.rs
rename to gui/src/graphics/vulkan/buffer.rs
index 7a1bcdfd7..6744c7e2a 100644
--- a/gui/src/screen/vulkan/buffer.rs
+++ b/gui/src/graphics/vulkan/buffer.rs
@@ -1,4 +1,4 @@
-use super::ScreenBuffer;
+use crate::graphics::ScreenBuffer;
 
 /// Manages Vulkan off-screen buffers.
 pub struct VulkanBuffer {}
diff --git a/gui/src/graphics/vulkan/mod.rs b/gui/src/graphics/vulkan/mod.rs
index 5f5aacbec..5e64d7092 100644
--- a/gui/src/graphics/vulkan/mod.rs
+++ b/gui/src/graphics/vulkan/mod.rs
@@ -1,20 +1,25 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
+use self::screen::VulkanScreen;
+use super::Graphics;
 use ash::vk::{ApplicationInfo, InstanceCreateInfo};
 use std::ffi::CStr;
 use thiserror::Error;
 
+mod buffer;
+mod screen;
+
 pub struct Vulkan {
     entry: ash::Entry,
     instance: ash::Instance,
     devices: Vec<VulkanPhysicalDevice>,
 }
 
-impl super::GraphicsApi for Vulkan {
+impl Graphics for Vulkan {
+    type Err = VulkanError;
     type PhysicalDevice = VulkanPhysicalDevice;
+    type Screen = VulkanScreen;
 
-    type CreateError = VulkanCreateError;
-
-    fn new() -> Result<Self, Self::CreateError> {
+    fn new() -> Result<Self, Self::Err> {
         let entry = ash::Entry::linked();
 
         let app_info = ApplicationInfo::default().application_name(c"Obliteration");
@@ -22,30 +27,28 @@ impl super::GraphicsApi for Vulkan {
         let create_info = InstanceCreateInfo::default().application_info(&app_info);
 
         let instance = unsafe { entry.create_instance(&create_info, None) }
-            .map_err(VulkanCreateError::CreateInstanceFailed)?;
+            .map_err(VulkanError::CreateInstanceFailed)?;
 
         let devices = unsafe { instance.enumerate_physical_devices() }
-            .map_err(VulkanCreateError::EnumeratePhysicalDevicesFailed)?
+            .map_err(VulkanError::EnumeratePhysicalDevicesFailed)?
             .into_iter()
-            .map(
-                |device| -> Result<VulkanPhysicalDevice, VulkanCreateError> {
-                    let properties = unsafe { instance.get_physical_device_properties(device) };
-
-                    let name = CStr::from_bytes_until_nul(unsafe {
-                        std::slice::from_raw_parts(
-                            properties.device_name.as_ptr().cast(),
-                            properties.device_name.len(),
-                        )
-                    })
-                    .map_err(|_| VulkanCreateError::DeviceNameInvalid)?
-                    .to_str()
-                    .map_err(VulkanCreateError::DeviceNameInvalidUtf8)?
-                    .to_owned();
-
-                    Ok(VulkanPhysicalDevice { device, name })
-                },
-            )
-            .collect::<Result<_, VulkanCreateError>>()?;
+            .map(|device| -> Result<VulkanPhysicalDevice, VulkanError> {
+                let properties = unsafe { instance.get_physical_device_properties(device) };
+
+                let name = CStr::from_bytes_until_nul(unsafe {
+                    std::slice::from_raw_parts(
+                        properties.device_name.as_ptr().cast(),
+                        properties.device_name.len(),
+                    )
+                })
+                .map_err(|_| VulkanError::DeviceNameInvalid)?
+                .to_str()
+                .map_err(VulkanError::DeviceNameInvalidUtf8)?
+                .to_owned();
+
+                Ok(VulkanPhysicalDevice { device, name })
+            })
+            .collect::<Result<_, VulkanError>>()?;
 
         Ok(Self {
             entry,
@@ -57,6 +60,10 @@ impl super::GraphicsApi for Vulkan {
     fn physical_devices(&self) -> &[Self::PhysicalDevice] {
         &self.devices
     }
+
+    fn create_screen(&mut self) -> Result<Self::Screen, Self::Err> {
+        todo!()
+    }
 }
 
 impl Drop for Vulkan {
@@ -76,9 +83,9 @@ impl super::PhysicalDevice for VulkanPhysicalDevice {
     }
 }
 
-/// Represents an error when [`Vulkan::new()`] fails.
+/// Implementation of [`Graphics::Err`] for Vulkan.
 #[derive(Debug, Error)]
-pub enum VulkanCreateError {
+pub enum VulkanError {
     #[error("couldn't create Vulkan instance")]
     CreateInstanceFailed(#[source] ash::vk::Result),
 
diff --git a/gui/src/screen/vulkan/mod.rs b/gui/src/graphics/vulkan/screen.rs
similarity index 96%
rename from gui/src/screen/vulkan/mod.rs
rename to gui/src/graphics/vulkan/screen.rs
index 23d8e40cd..c7f0e1b68 100644
--- a/gui/src/screen/vulkan/mod.rs
+++ b/gui/src/graphics/vulkan/screen.rs
@@ -1,14 +1,12 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
-use self::buffer::VulkanBuffer;
-use crate::graphics::{Screen, ScreenBuffer};
+use super::buffer::VulkanBuffer;
+use crate::graphics::Screen;
 use crate::vmm::VmmScreen;
 use ash::vk::{DeviceCreateInfo, DeviceQueueCreateInfo, Handle, QueueFlags};
 use ash::Device;
 use std::sync::Arc;
 use thiserror::Error;
 
-mod buffer;
-
 /// Implementation of [`Screen`] using Vulkan.
 pub struct VulkanScreen {
     buffer: Arc<VulkanBuffer>,
diff --git a/gui/src/lib.rs b/gui/src/lib.rs
index 9d036a7f3..d02f61265 100644
--- a/gui/src/lib.rs
+++ b/gui/src/lib.rs
@@ -8,7 +8,6 @@ mod hv;
 mod param;
 mod pkg;
 mod profile;
-mod screen;
 mod string;
 mod system;
 mod vmm;
diff --git a/gui/src/main.rs b/gui/src/main.rs
index 9b03cd0be..69438483e 100644
--- a/gui/src/main.rs
+++ b/gui/src/main.rs
@@ -1,10 +1,9 @@
 #![windows_subsystem = "windows"]
 
-use self::graphics::{GraphicsApi, PhysicalDevice, Screen};
+use self::graphics::{Graphics, PhysicalDevice, Screen};
 use self::profile::Profile;
-use self::screen::DefaultScreen;
 use self::ui::ErrorDialog;
-use self::vmm::{Vmm, VmmEvent};
+use self::vmm::VmmEvent;
 use args::CliArgs;
 use clap::Parser;
 use debug::DebugServer;
@@ -25,7 +24,6 @@ mod pkg;
 mod profile;
 #[cfg(unix)]
 mod rlim;
-mod screen;
 mod string;
 mod system;
 mod ui;
@@ -47,10 +45,16 @@ fn run() -> Result<(), ApplicationError> {
     #[cfg(unix)]
     rlim::set_rlimit_nofile().map_err(ApplicationError::FdLimit)?;
 
+    // Initialize graphics engine.
+    let mut graphics = match graphics::DefaultApi::new() {
+        Ok(v) => v,
+        Err(e) => return Err(ApplicationError::InitGraphics(Box::new(e))),
+    };
+
     // TODO: check if already configured and skip wizard
     run_wizard().map_err(ApplicationError::RunWizard)?;
 
-    let vmm = if let Some(debug_addr) = args.debug_addr() {
+    let args = if let Some(debug_addr) = args.debug_addr() {
         let kernel_path = get_kernel_path(&args)?;
 
         let debug_server = DebugServer::new(debug_addr)
@@ -60,9 +64,6 @@ fn run() -> Result<(), ApplicationError> {
             .accept()
             .map_err(ApplicationError::CreateDebugClient)?;
 
-        let _graphics_api =
-            graphics::DefaultApi::new().map_err(ApplicationError::InitGraphicsApi)?;
-
         let profiles = load_profiles()?;
 
         // TODO: handle events
@@ -73,29 +74,24 @@ fn run() -> Result<(), ApplicationError> {
             VmmEvent::Error { reason } => {}
         };
 
-        let vmm = Vmm::new(
-            kernel_path,
-            todo!(),
-            &profiles[0],
-            Some(debug_client),
-            event_handler,
-        )
-        .map_err(ApplicationError::RunVmm)?;
-
         todo!()
     } else {
-        run_launcher()?
+        run_launcher(&graphics)?
     };
 
-    let Some(vmm) = vmm else {
+    let Some(args) = args else {
         return Ok(());
     };
 
     // Setup VMM screen.
-    let mut screen = DefaultScreen::new().map_err(ApplicationError::CreateScreen)?;
+    let mut screen = graphics
+        .create_screen()
+        .map_err(|e| ApplicationError::CreateScreen(Box::new(e)))?;
 
     // TODO: Start VMM.
-    screen.run().map_err(ApplicationError::RunScreen)?;
+    screen
+        .run()
+        .map_err(|e| ApplicationError::RunScreen(Box::new(e)))?;
 
     Ok(())
 }
@@ -107,7 +103,7 @@ fn load_profiles() -> Result<Vec<Profile>, ApplicationError> {
     Ok(profiles)
 }
 
-fn run_launcher() -> Result<Option<Vmm>, ApplicationError> {
+fn run_launcher(graphics: &impl Graphics) -> Result<Option<VmmArgs>, ApplicationError> {
     // Create window and register callback handlers.
     let win = ui::MainWindow::new().map_err(ApplicationError::CreateMainWindow)?;
     let start = Rc::new(RefCell::new(false));
@@ -122,8 +118,6 @@ fn run_launcher() -> Result<Option<Vmm>, ApplicationError> {
         }
     });
 
-    let graphics_api = graphics::DefaultApi::new().map_err(ApplicationError::InitGraphicsApi)?;
-
     let profiles = load_profiles()?;
 
     setup_globals(&win);
@@ -137,7 +131,7 @@ fn run_launcher() -> Result<Option<Vmm>, ApplicationError> {
     win.set_profiles(profiles);
 
     let physical_devices = ModelRc::new(VecModel::from_iter(
-        graphics_api
+        graphics
             .physical_devices()
             .iter()
             .map(|p| SharedString::from(p.name())),
@@ -274,6 +268,10 @@ fn run_wizard() -> Result<(), slint::PlatformError> {
     })
 }
 
+/// Encapsulates arguments for [`Vmm::new()`].
+struct VmmArgs {}
+
+/// Represents an error when [`run()`] fails.
 #[derive(Debug, Error)]
 enum ApplicationError {
     #[error(transparent)]
@@ -301,18 +299,15 @@ enum ApplicationError {
     #[error("failed to create main window")]
     CreateMainWindow(#[source] slint::PlatformError),
 
-    #[error("failed to initialize graphics API")]
-    InitGraphicsApi(#[source] <graphics::DefaultApi as GraphicsApi>::CreateError),
-
-    #[error("failed to run vmm")]
-    RunVmm(#[source] vmm::VmmError),
+    #[error("couldn't initialize graphics engine")]
+    InitGraphics(#[source] Box<dyn std::error::Error>),
 
     #[error("failed to run main window")]
     RunMainWindow(#[source] slint::PlatformError),
 
     #[error("couldn't create VMM screen")]
-    CreateScreen(#[source] screen::ScreenError),
+    CreateScreen(#[source] Box<dyn std::error::Error>),
 
     #[error("couldn't run VMM screen")]
-    RunScreen(#[source] <DefaultScreen as Screen>::RunErr),
+    RunScreen(#[source] Box<dyn std::error::Error>),
 }
diff --git a/gui/src/screen/mod.rs b/gui/src/screen/mod.rs
deleted file mode 100644
index 0a0d14083..000000000
--- a/gui/src/screen/mod.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-// SPDX-License-Identifier: MIT OR Apache-2.0
-#[cfg_attr(target_os = "macos", path = "metal/mod.rs")]
-#[cfg_attr(not(target_os = "macos"), path = "vulkan/mod.rs")]
-mod engine;
-
-#[cfg(not(target_os = "macos"))]
-pub type DefaultScreen = self::engine::VulkanScreen;
-
-#[cfg(target_os = "macos")]
-pub type DefaultScreen = self::engine::MetalScreen;
-
-#[cfg(not(target_os = "macos"))]
-pub type ScreenError = self::engine::VulkanScreenError;
-
-#[cfg(target_os = "macos")]
-pub type ScreenError = self::engine::MetalError;
diff --git a/gui/src/vmm/ffi.rs b/gui/src/vmm/ffi.rs
deleted file mode 100644
index b44a960be..000000000
--- a/gui/src/vmm/ffi.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-use super::Vmm;
-use std::sync::atomic::Ordering;
-
-#[no_mangle]
-pub unsafe extern "C" fn vmm_free(vmm: *mut Vmm) {
-    drop(Box::from_raw(vmm));
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn vmm_shutdown(vmm: *mut Vmm) {
-    (*vmm).shutdown.store(true, Ordering::Relaxed);
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn vmm_shutting_down(vmm: *mut Vmm) -> bool {
-    (*vmm).shutdown.load(Ordering::Relaxed)
-}
diff --git a/gui/src/vmm/mod.rs b/gui/src/vmm/mod.rs
index b40d3a03b..b6fa3b57b 100644
--- a/gui/src/vmm/mod.rs
+++ b/gui/src/vmm/mod.rs
@@ -18,7 +18,7 @@ use kernel::{KernelError, ProgramHeaderError};
 use obconf::{BootEnv, ConsoleType, Vm};
 use std::cmp::max;
 use std::error::Error;
-use std::ffi::{c_char, CStr};
+use std::ffi::CStr;
 use std::io::Read;
 use std::num::NonZero;
 use std::path::{Path, PathBuf};
@@ -31,8 +31,6 @@ use thiserror::Error;
 mod arch;
 mod cpu;
 mod debug;
-#[cfg(feature = "qt")]
-mod ffi;
 mod hw;
 mod kernel;
 mod ram;
@@ -60,23 +58,17 @@ fn get_page_size() -> Result<NonZero<usize>, std::io::Error> {
 }
 
 /// Manage a virtual machine that run the kernel.
-pub struct Vmm {
-    cpu: CpuManager<crate::hv::Default, crate::screen::DefaultScreen>, // Drop first.
-    screen: crate::screen::DefaultScreen,
-    gdb: Option<
-        GdbStubStateMachine<
-            'static,
-            CpuManager<crate::hv::Default, crate::screen::DefaultScreen>,
-            DebugClient,
-        >,
-    >,
+pub struct Vmm<S: Screen> {
+    cpu: CpuManager<crate::hv::Default, S>, // Drop first.
+    screen: S,
+    gdb: Option<GdbStubStateMachine<'static, CpuManager<crate::hv::Default, S>, DebugClient>>,
     shutdown: Arc<AtomicBool>,
 }
 
-impl Vmm {
+impl<S: Screen> Vmm<S> {
     pub fn new(
         kernel_path: impl AsRef<Path>,
-        screen: crate::screen::DefaultScreen,
+        screen: S,
         profile: &Profile,
         debugger: Option<DebugClient>,
         event_handler: impl Fn(VmmEvent) + Send + Sync + 'static,
@@ -398,7 +390,7 @@ impl Vmm {
     }
 }
 
-impl Drop for Vmm {
+impl<S: Screen> Drop for Vmm<S> {
     fn drop(&mut self) {
         // Set shutdown flag before dropping the other fields so their background thread can stop
         // before they try to join with it.