[patch] Refine SCREEN_INFO sanity check for vgacon initialization.

[patch] Refine SCREEN_INFO sanity check for vgacon initialization.

[Gerd Hoffmann]

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   Hi,

Checking video mode field only to see whenever SCREEN_INFO is
initialized is not enougth, in some cases it is zero although
a vga card is present.  Lets additionally check cols and lines.

Updates f82af20e1a028e16b9bb11da081fa1148d40fa6a, should go
into 2.6.22.

please apply,
   Gerd


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Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is
initialized is not enougth, in some cases it is zero although
a vga card is present.  Lets additionally check cols and lines.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Alan <alan@lxorguk.ukuu.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Eric W. Biederman <ebiederm@xmission.com>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================
--- vanilla-2.6.21-git11.orig/drivers/video/console/vgacon.c
+++ vanilla-2.6.21-git11/drivers/video/console/vgacon.c
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
 	}
 
+	/* SCREEN_INFO initialized? */
+	if ((ORIG_VIDEO_MODE  == 0) &&
+	    (ORIG_VIDEO_LINES == 0) &&
+	    (ORIG_VIDEO_COLS  == 0))
+		goto no_vga;
+
 	/* VGA16 modes are not handled by VGACON */
-	if ((ORIG_VIDEO_MODE == 0x00) ||	/* SCREEN_INFO not initialized */
-	    (ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
+	if ((ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
 	    (ORIG_VIDEO_MODE == 0x0E) ||	/* 640x200/4 */
 	    (ORIG_VIDEO_MODE == 0x10) ||	/* 640x350/4 */
 	    (ORIG_VIDEO_MODE == 0x12) ||	/* 640x480/4 */

Re: [patch] Refine SCREEN_INFO sanity check for vgacon initialization.

[Eric W. Biederman]

Gerd Hoffmann <kraxel@redhat.com> writes:

>   Hi,
>
> Checking video mode field only to see whenever SCREEN_INFO is
> initialized is not enougth, in some cases it is zero although
> a vga card is present.  Lets additionally check cols and lines.

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

>
> Updates f82af20e1a028e16b9bb11da081fa1148d40fa6a, should go
> into 2.6.22.
>
> please apply,
>   Gerd
>
> Refine SCREEN_INFO sanity check for vgacon initialization.
>
> Checking video mode field only to see whenever SCREEN_INFO is
> initialized is not enougth, in some cases it is zero although
> a vga card is present.  Lets additionally check cols and lines.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Andi Kleen <ak@suse.de>
> Cc: Alan <alan@lxorguk.ukuu.org.uk>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> ---
>  drivers/video/console/vgacon.c |    9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
> ===================================================================
> --- vanilla-2.6.21-git11.orig/drivers/video/console/vgacon.c
> +++ vanilla-2.6.21-git11/drivers/video/console/vgacon.c
> @@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
>  #endif
>  	}
>  
> +	/* SCREEN_INFO initialized? */
> +	if ((ORIG_VIDEO_MODE  == 0) &&
> +	    (ORIG_VIDEO_LINES == 0) &&
> +	    (ORIG_VIDEO_COLS  == 0))
> +		goto no_vga;
> +
>  	/* VGA16 modes are not handled by VGACON */
> - if ((ORIG_VIDEO_MODE == 0x00) || /* SCREEN_INFO not initialized */
> -	    (ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
> +	if ((ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
>  	    (ORIG_VIDEO_MODE == 0x0E) ||	/* 640x200/4 */
>  	    (ORIG_VIDEO_MODE == 0x10) ||	/* 640x350/4 */
>  	    (ORIG_VIDEO_MODE == 0x12) ||	/* 640x480/4 */