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, 11 insertions, 0 deletions

diff --git a/AK/Format.h b/AK/Format.h
index 5e05a55ac1..f1ef2e8fb8 100644
--- a/AK/Format.h
+++ b/AK/Format.h
@@ -436,6 +436,16 @@ void dmesgln(CheckedFormatString<Parameters...>&& fmt, const Parameters&... para
 {
     vdmesgln(fmt.view(), VariadicFormatParams { parameters... });
 }
+
+void v_critical_dmesgln(StringView fmtstr, TypeErasedFormatParams);
+
+// be very careful to not cause any allocations here, since we could be in
+// a very unstable situation
+template<typename... Parameters>
+void critical_dmesgln(CheckedFormatString<Parameters...>&& fmt, const Parameters&... parameters)
+{
+    v_critical_dmesgln(fmt.view(), VariadicFormatParams { parameters... });
+}
 #endif
 
 template<typename T, typename = void>
@@ -492,6 +502,7 @@ struct Formatter<FormatString> : Formatter<String> {
 } // namespace AK
 
 #ifdef KERNEL
+using AK::critical_dmesgln;
 using AK::dmesgln;
 #else
 using AK::out;