Kernel/Graphics + SystemServer: Support text mode properly

As we removed the support of VBE modesetting that was done by GRUB early
on boot, we need to determine if we can modeset the resolution with our
drivers, and if not, we should enable text mode and ensure that
SystemServer knows about it too.

Also, SystemServer should first check if there's a framebuffer device
node, which is an indication that text mode was not even if it was
requested. Then, if it doesn't find it, it should check what boot_mode
argument the user specified (in case it's self-test). This way if we
try to use bochs-display device (which is not VGA compatible) and
request a text mode, it will not honor the request and will continue
with graphical mode.

Also try to print critical messages with mininum memory allocations
possible.

In LibVT, We make the implementation flexible for kernel-specific
methods that are implemented in ConsoleImpl class.

1 files changed, 83 insertions, 13 deletions

diff --git a/Kernel/TTY/VirtualConsole.h b/Kernel/TTY/VirtualConsole.h
index 10b04771f8..3ad2c0f703 100644
--- a/Kernel/TTY/VirtualConsole.h
+++ b/Kernel/TTY/VirtualConsole.h
@@ -1,35 +1,91 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #pragma once
 
+#include <AK/Noncopyable.h>
+#include <AK/NonnullOwnPtrVector.h>
+#include <AK/String.h>
+#include <AK/Vector.h>
+#include <Kernel/API/KeyCode.h>
 #include <Kernel/ConsoleDevice.h>
 #include <Kernel/Devices/HID/HIDManagement.h>
+#include <Kernel/Graphics/Console/Console.h>
 #include <Kernel/TTY/TTY.h>
+#include <LibVT/Attribute.h>
+#include <LibVT/Position.h>
 #include <LibVT/Terminal.h>
 
 namespace Kernel {
 
-static constexpr unsigned s_max_virtual_consoles = 6;
+class ConsoleManagement;
+class VirtualConsole;
+// FIXME: This implementation has no knowledge about keeping terminal history...
+class ConsoleImpl final : public VT::Terminal {
+public:
+    explicit ConsoleImpl(VirtualConsole&);
+
+    virtual void set_size(u16 columns, u16 rows) override;
+
+private:
+    virtual void invalidate_cursor() override;
+    virtual void clear() override;
+    virtual void clear_including_history() override;
+
+    virtual void scroll_up() override;
+    virtual void scroll_down() override;
+    virtual void newline() override;
+    virtual void put_character_at(unsigned row, unsigned column, u32 ch) override;
+    virtual void set_window_title(const String&) override;
+
+    virtual void ICH(Parameters) override;
+
+    virtual void IL(Parameters) override;
+    virtual void DCH(Parameters) override;
+    virtual void DL(Parameters) override;
+};
 
 class VirtualConsole final : public TTY
     , public KeyboardClient
     , public VT::TerminalClient {
     AK_MAKE_ETERNAL
+    friend class ConsoleManagement;
+    friend class ConsoleImpl;
+    friend class VT::Terminal;
+
 public:
-    VirtualConsole(const unsigned index);
+    struct Line {
+        bool dirty;
+    };
+
+    struct Cell {
+        void clear()
+        {
+            ch = ' ';
+            attribute.reset();
+        }
+        char ch;
+        VT::Attribute attribute;
+    };
+
+public:
+    static NonnullRefPtr<VirtualConsole> create(size_t index);
+
     virtual ~VirtualConsole() override;
 
-    static void switch_to(unsigned);
-    static void initialize();
+    size_t index() const { return m_index; }
 
     bool is_graphical() { return m_graphical; }
     void set_graphical(bool graphical);
 
+    void emit_char(char);
+
 private:
+    VirtualConsole(const unsigned index);
     // ^KeyboardClient
     virtual void on_key_pressed(KeyEvent) override;
 
@@ -53,23 +109,37 @@ private:
     virtual String device_name() const override;
 
     void set_active(bool);
-
-    void flush_vga_cursor();
     void flush_dirty_lines();
 
     unsigned m_index;
     bool m_active { false };
     bool m_graphical { false };
 
-    void clear_vga_row(u16 row);
-    void set_vga_start_row(u16 row);
-    u16 m_vga_start_row { 0 };
-    u16 m_current_vga_start_address { 0 };
-    u8* m_current_vga_window { nullptr };
+    String m_tty_name;
+    RecursiveSpinLock m_lock;
 
-    VT::Terminal m_terminal;
+private:
+    void invalidate_cursor(size_t row);
 
-    String m_tty_name;
+    void clear();
+
+    void inject_string(const StringView&);
+
+    Cell& cell_at(size_t column, size_t row);
+
+    typedef Vector<unsigned, 4> ParamVector;
+
+    void on_code_point(u32);
+
+    void scroll_down();
+    void scroll_up();
+    void newline();
+    void clear_line(size_t index);
+    void put_character_at(unsigned row, unsigned column, u32 ch, const VT::Attribute&);
+
+    OwnPtr<Region> m_cells;
+    Vector<VirtualConsole::Line> m_lines;
+    ConsoleImpl m_console_impl;
 };
 
 }