Kernel: Allow the user to specify the virtual console when booting

Author: https://github.com/supercomputer7
Commit: https://github.com/SerenityOS/serenity/commit/ab52108982a
Pull-request: https://github.com/SerenityOS/serenity/pull/6277
Reviewed-by: https://github.com/ElectrodeYT
Reviewed-by: https://github.com/awesomekling

Kernel/CommandLine.cpp

@@ -201,4 +201,13 @@ Vector<String> CommandLine::userspace_init_args() const
     return init_args;
 }
 
+UNMAP_AFTER_INIT size_t CommandLine::switch_to_tty() const
+{
+    const auto default_tty = lookup("switch_to_tty").value_or("1");
+    auto switch_tty_number = default_tty.to_uint();
+    if (switch_tty_number.has_value() && switch_tty_number.value() >= 1) {
+        return switch_tty_number.value() - 1;
+    }
+    PANIC("Invalid default tty value: {}", default_tty);
+}
 }

Kernel/CommandLine.h

@@ -72,6 +72,7 @@ public:
     [[nodiscard]] String userspace_init() const;
     [[nodiscard]] Vector<String> userspace_init_args() const;
     [[nodiscard]] String root_device() const;
+    [[nodiscard]] size_t switch_to_tty() const;
 
 private:
     CommandLine(const String&);

Kernel/TTY/ConsoleManagement.cpp

@@ -5,8 +5,10 @@
  */
 
 #include <AK/Singleton.h>
+#include <Kernel/CommandLine.h>
 #include <Kernel/Debug.h>
 #include <Kernel/Graphics/GraphicsManagement.h>
+#include <Kernel/Panic.h>
 #include <Kernel/TTY/ConsoleManagement.h>
 
 namespace Kernel {
@@ -39,7 +41,11 @@ UNMAP_AFTER_INIT void ConsoleManagement::initialize()
         m_consoles.append(VirtualConsole::create(index));
     }
     // Note: By default the active console is the first one.
-    m_active_console = m_consoles[0];
+    auto tty_number = kernel_command_line().switch_to_tty();
+    if (tty_number > m_consoles.size()) {
+        PANIC("Switch to tty value is invalid: {} ", tty_number);
+    }
+    m_active_console = m_consoles[tty_number];
     ScopedSpinLock lock(m_lock);
     m_active_console->set_active(true);
 }

Kernel/init.cpp

@@ -166,7 +166,6 @@ extern "C" UNMAP_AFTER_INIT [[noreturn]] void init()
     PCI::initialize();
     GraphicsManagement::the().initialize();
     ConsoleManagement::the().initialize();
-    ConsoleManagement::the().switch_to(0);
 
     Thread::initialize();
     Process::initialize();