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.

Userland/Libraries/LibVT/Terminal.cpp

@@ -9,19 +9,23 @@
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
 #include <LibVT/Terminal.h>
+#ifdef KERNEL
+#    include <Kernel/TTY/VirtualConsole.h>
+#endif
 
 namespace VT {
 
+#ifndef KERNEL
 Terminal::Terminal(TerminalClient& client)
+#else
+Terminal::Terminal(Kernel::VirtualConsole& client)
+#endif
     : m_client(client)
     , m_parser(*this)
 {
 }
 
-Terminal::~Terminal()
-{
-}
-
+#ifndef KERNEL
 void Terminal::clear()
 {
     for (size_t i = 0; i < rows(); ++i)
@@ -38,6 +42,7 @@ void Terminal::clear_including_history()
 
     m_client.terminal_history_changed();
 }
+#endif
 
 void Terminal::alter_mode(bool should_set, Parameters params, Intermediates intermediates)
 {
@@ -445,6 +450,7 @@ void Terminal::SD(Parameters params)
         scroll_down();
 }
 
+#ifndef KERNEL
 void Terminal::IL(Parameters params)
 {
     int count = 1;
@@ -461,12 +467,14 @@ void Terminal::IL(Parameters params)
 
     m_need_full_flush = true;
 }
+#endif
 
 void Terminal::DA(Parameters)
 {
     emit_string("\033[?1;0c");
 }
 
+#ifndef KERNEL
 void Terminal::DL(Parameters params)
 {
     int count = 1;
@@ -511,6 +519,7 @@ void Terminal::DCH(Parameters params)
 
     line.set_dirty(true);
 }
+#endif
 
 void Terminal::newline()
 {
@@ -527,6 +536,7 @@ void Terminal::carriage_return()
     set_cursor(m_cursor_row, 0);
 }
 
+#ifndef KERNEL
 void Terminal::scroll_up()
 {
     // NOTE: We have to invalidate the cursor first.
@@ -550,6 +560,20 @@ void Terminal::scroll_down()
     m_need_full_flush = true;
 }
 
+void Terminal::put_character_at(unsigned row, unsigned column, u32 code_point)
+{
+    VERIFY(row < rows());
+    VERIFY(column < columns());
+    auto& line = m_lines[row];
+    line.set_code_point(column, code_point);
+    line.attribute_at(column) = m_current_attribute;
+    line.attribute_at(column).flags |= Attribute::Touched;
+    line.set_dirty(true);
+
+    m_last_code_point = code_point;
+}
+#endif
+
 void Terminal::set_cursor(unsigned a_row, unsigned a_column)
 {
     unsigned row = min(a_row, m_rows - 1u);
@@ -565,19 +589,6 @@ void Terminal::set_cursor(unsigned a_row, unsigned a_column)
     invalidate_cursor();
 }
 
-void Terminal::put_character_at(unsigned row, unsigned column, u32 code_point)
-{
-    VERIFY(row < rows());
-    VERIFY(column < columns());
-    auto& line = m_lines[row];
-    line.set_code_point(column, code_point);
-    line.attribute_at(column) = m_current_attribute;
-    line.attribute_at(column).flags |= Attribute::Touched;
-    line.set_dirty(true);
-
-    m_last_code_point = code_point;
-}
-
 void Terminal::NEL()
 {
     newline();
@@ -607,6 +618,7 @@ void Terminal::DSR(Parameters params)
     }
 }
 
+#ifndef KERNEL
 void Terminal::ICH(Parameters params)
 {
     int num = 0;
@@ -628,6 +640,7 @@ void Terminal::ICH(Parameters params)
 
     line.set_dirty(true);
 }
+#endif
 
 void Terminal::on_input(u8 byte)
 {
@@ -837,6 +850,7 @@ void Terminal::execute_osc_sequence(OscParameters parameters, u8 last_byte)
                 // Should we expose the raw OSC string from the parser? Or join by semicolon?
                 break;
             case 8:
+#ifndef KERNEL
                 if (parameters.size() < 2) {
                     dbgln("Attempted to set href but gave too few parameters");
                 } else if (parameters[2].is_empty()) {
@@ -847,6 +861,7 @@ void Terminal::execute_osc_sequence(OscParameters parameters, u8 last_byte)
                     // FIXME: Respect the provided ID
                     m_current_attribute.href_id = String::number(m_next_href_id++);
                 }
+#endif
                 break;
             case 9:
                 if (parameters.size() < 2 || parameters[1].is_empty() || parameters[2].is_empty())
@@ -1034,6 +1049,7 @@ void Terminal::unimplemented_osc_sequence(OscParameters parameters, u8 last_byte
     dbgln("{}", builder.string_view());
 }
 
+#ifndef KERNEL
 void Terminal::set_size(u16 columns, u16 rows)
 {
     if (!columns)
@@ -1073,7 +1089,9 @@ void Terminal::set_size(u16 columns, u16 rows)
 
     m_client.terminal_did_resize(m_columns, m_rows);
 }
+#endif
 
+#ifndef KERNEL
 void Terminal::invalidate_cursor()
 {
     m_lines[m_cursor_row].set_dirty(true);
@@ -1090,5 +1108,6 @@ Attribute Terminal::attribute_at(const Position& position) const
         return {};
     return line.attribute_at(position.column());
 }
+#endif
 
 }