Commit:     2ae854777592856ad8ce4d4cdb6114804e2e28f6
Parent:     32dd38030b3b4ca0aa18a5402059de27bf69ed6b
Author:     Antonino A. Daplas <[EMAIL PROTECTED]>
AuthorDate: Tue May 8 00:40:06 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue May 8 11:15:33 2007 -0700

    vgacon: disallow console operations when in KD_GRAPHICS mode
    Reported by James Pearson as:
         boot to run level 3
         if not root, then make sure /dev/console is writeable
         login and type:
         setterm -blank 0
         start X
         type into an xterm:
         while true; do echo "" > /dev/console; usleep 100000; done
         while the above loop is running switch to the text console and back
         again (Ctrl-Alt-F1 then Ctrl-Alt-F7)
         ... and the screen will be shifting (and wrapping) to the left.
    This problem stems from continuously writing text to the system console 
    is in KD_TEXT mode) while the foreground console is in KD_GRAPHICS
    mode. Somewhere along the way, console printing got confused and omitted the
    KD_GRAPHICS/KD_TEXT test.  Thus, vgacon attempted to scroll the screen of X,
    which causes X to shift.
    Fix by disallowing vgacon to touch the hardware when the vc is in 
    mode. A definitive fix entails a full audit of the console code.
    Signed-off-by: Antonino Daplas <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 drivers/video/console/vgacon.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index d0d2733..2460b82 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -660,6 +660,9 @@ static void vgacon_set_cursor_size(int xpos, int from, int 
 static void vgacon_cursor(struct vc_data *c, int mode)
+       if (c->vc_mode != KD_TEXT)
+               return;
        switch (mode) {
@@ -1318,7 +1321,7 @@ static int vgacon_scroll(struct vc_data *c, int t, int b, 
int dir,
        unsigned long oldo;
        unsigned int delta;
-       if (t || b != c->vc_rows || vga_is_gfx)
+       if (t || b != c->vc_rows || vga_is_gfx || c->vc_mode != KD_TEXT)
                return 0;
        if (!vga_hardscroll_enabled || lines >= c->vc_rows / 2)
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