message: define configuration attribute "vga" to enable VGA support
diff: @@ -34,6 +34,7 @@ pub mod pit;
  pub mod processor;
  pub mod scheduler;
  pub mod serial;
  +#[cfg(feature = "vga")]
  pub mod vga;
  pub use arch::x86_64::apic::get_core_id_for_cpu_number;
  @@ -81,7 +82,8 @@ pub fn message_output_init() {
  pub fn output_message_byte(byte: u8) {
  COM1.write_byte(byte);
  - if is_uhyve() == false {
  + if cfg!(feature = "vga") && is_uhyve() == false {
  + #[cfg(feature = "vga")]
  vga::write_byte(byte);
  }
  }
  @@ -90,7 +92,8 @@ pub fn output_message_byte(byte: u8) {
  pub fn boot_processor_init() {
  processor::detect_features();
  processor::configure();
  - if is_uhyve() == false {
  + if cfg!(feature = "vga") && is_uhyve() == false {
  + #[cfg(feature = "vga")]
  vga::init();
  }
  ::mm::init();
  