[PATCH 1/2] fix vc->vc_origin on take_over_console.

From: qiaochong
Date: Thu Jun 10 2010 - 20:27:55 EST

kernel will die on some platform when switch from vga mode to framebuffer mode.
The reason of this bug is that bind_con_driver reset vc->vc_origin to (unsigned long)vc->vc_screenbuf.
On vgacon vc->vc_origin is not releated to vc->vc_screenbuf,if set
vc->vc_origin to vc->vc_screenbuf,kernel will die on vc_do_resize.

static int vc_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
struct vc_data *vc, unsigned int cols, unsigned int lines)
unsigned long old_origin, new_origin, new_scr_end, rlth, rrem, err = 0;
unsigned int old_cols, old_rows, old_row_size, old_screen_size;
unsigned int new_cols, new_rows, new_row_size, new_screen_size;
unsigned int end, user;
end = (old_rows > new_rows) ? old_origin +
(old_row_size * new_rows) :

here for a test from vgacon to framebuffer:
the code bellow will copy memory from 0x810814a0 to 0xb00b8fa0,
this will cover kernel code,kernel died here.

while (old_origin < end) {

scr_memcpyw((unsigned short *) new_origin,
(unsigned short *) old_origin, rlth);
if (rrem)
scr_memsetw((void *)(new_origin + rlth),
vc->vc_video_erase_char, rrem);
old_origin += old_row_size;
new_origin += new_row_size;


Signed-off-by: qiaochong <qiaochong@xxxxxxxxxxx>
drivers/char/vt.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 50faa1f..6a22f87 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -3063,6 +3063,7 @@ static int bind_con_driver(const struct consw *csw, int first, int last,

old_was_color = vc->vc_can_do_color;
+ if(!vc->vc_origin)
vc->vc_origin = (unsigned long)vc->vc_screenbuf;
visual_init(vc, i, 0);

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