x86: Allow selection of graphical video modes during boot.

The 'vga=' boot option is extended as follows:

----------
 'vga=<mode-specifier>[,keep]' where <mode-specifier> is one of:

   'vga=ask':
      display a vga menu of available modes

   'vga=text-80x<rows>':
      text mode, where <rows> is one of {25,28,30,34,43,50,60}

   'vga=gfx-<width>x<height>x<depth>':
      graphics mode, e.g., vga=gfx-1024x768x16

   'vga=mode-<mode>:
      specifies a mode as specified in 'vga=ask' menu
      (NB. menu modes are displayed in hex, so mode numbers here must
           be prefixed with '0x' (e.g., 'vga=mode-0x0318'))

 The option 'keep' causes Xen to continue to print to the VGA console even
 after domain 0 starts to boot. The default behaviour is to relinquish
 control of the console to domain 0.
----------

Signed-off-by: Keir Fraser <keir@xensource.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/xen/include/xen/vga.h b/xen/include/xen/vga.h
index 3431d625f7..e0737659c1 100644
--- a/xen/include/xen/vga.h
+++ b/xen/include/xen/vga.h
@@ -12,6 +12,7 @@
 #include <xen/config.h>
 
 #ifdef CONFIG_VGA
+extern struct xen_vga_console_info vga_console_info;
 void vga_init(void);
 void vga_endboot(void);
 void vga_putchar(int c);