[PATCH 3/4] probe for quietboot in vgabios

[Cory Fields <FOSS@AtlasTechnologiesInc.com>]

 If quietboot is set disable all normal text output
 Errors should still be shown

 Signed-off-by: Cory Fields <FOSS@AtlasTechnologiesInc.com>

---
 vgabios/vgabios.c |   17 ++++++++++++++++-
 1 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/vgabios/vgabios.c b/vgabios/vgabios.c
index e6fe2a0..923ea66 100644
--- a/vgabios/vgabios.c
+++ b/vgabios/vgabios.c
@@ -55,6 +55,10 @@
 #endif
 
 #define USE_BX_INFO
+#define BX_CFG_CTL_PORT    0x510
+#define BX_CFG_DATA_PORT   0x511
+#define BX_CFG_SIGNATURE   0x00
+#define BX_CFG_QUIETBOOT   0x08
 
 /* Declares */
 static Bit8u          read_byte();
@@ -250,6 +254,10 @@ vgabios_init_func:
   call cirrus_init
 #endif
 
+ call   _qemu_quietboot_probe
+ test   al,al
+ jnz    skip_display
+
 ;; display splash screen
   call _display_splash_screen
 
@@ -269,7 +277,7 @@ vgabios_init_func:
 ;; show cirrus info
   call cirrus_display_info
 #endif
-
+skip_display:
   retf
 ASM_END
 
@@ -3839,6 +3847,13 @@ void printf(s)
 #endif
 
 // --------------------------------------------------------------------------------------------
+static int qemu_quietboot_probe()
+{
+  outw(BX_CFG_CTL_PORT, BX_CFG_QUIETBOOT);  
+
+  if (inb(BX_CFG_DATA_PORT)) return 1;
+  return 0;
+}
 
 ASM_START 
 ;; DATA_SEG_DEFS_HERE
-- 
1.6.0.6