vt/console: try harder to print output when panicing

Jesse's initial patch commit said:

"At panic time (i.e.  when oops_in_progress is set) we should try a bit
harder to update the screen and make sure output gets to the VT, since
some drivers are capable of flipping back to it.

So make sure we try to unblank and update the display if called from a
panic context."

I've enhanced this to add a flag to the vc that console layer can set to
indicate they want this behaviour to occur.  This also adds support to
fbcon for that flag and adds an fb flag for drivers to indicate they want
to use the support.  It enables this for KMS drivers.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: James Simmons <jsimmons@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 38fe59dc89ae..d7d9acdccffb 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -105,6 +105,7 @@ struct vc_data {
 	struct vc_data **vc_display_fg;		/* [!] Ptr to var holding fg console for this display */
 	unsigned long	vc_uni_pagedir;
 	unsigned long	*vc_uni_pagedir_loc;  /* [!] Location of uni_pagedir variable for this console */
+	bool vc_panic_force_write; /* when oops/panic this VC can accept forced output/blanking */
 	/* additional information is in vt_kern.h */
 };