diff options
authorNicolas Pitre <>2019-01-10 01:49:28 -0500
committerNicolas Pitre <>2019-01-10 16:29:11 -0500
commit7683eca8237b2f43f5ad519d264f450cd73540c9 (patch)
parentcf4549ef52e0682323c6fc18545f986f89423d57 (diff)
vgacon: unconfuse vc_origin when using soft scrollbackvt_fixes
When CONFIG_VGACON_SOFT_SCROLLBACK is selected, the VGA display memory index and vc_visible_origin don't change when scrollback is activated. The actual screen content is saved away and the scrollbackdata is copied over it. However the vt code, and /dev/vcs devices in particular, still expect vc_origin to always point at the actual screen content not the displayed scrollback content. So adjust vc_origin to point at the saved screen content when scrollback is active and set it back to vc_visible_origin when restoring the screen. This fixes /dev/vcsa<n> that return scrollback content when they shouldn't (onli /dev/vcsa without a number should), and also fixes /dev/vcsu that should return scrollback content when scrollback is active but currently doesn't. An unnecessary call to vga_set_mem_top() is also removed. Signed-off-by: Nicolas Pitre <> Cc: # v4.19+ --- I tagged it for stable starting with v4.19 as this is the kernel that introduced /dev/vcsu* which is directly affected. Users of earlier kernels most likely won't care.
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 09731b2f6815..c6b3bdbbdbc9 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -271,6 +271,7 @@ static void vgacon_scrollback_update(struct vc_data *c, int t, int count)
static void vgacon_restore_screen(struct vc_data *c)
+ c->vc_origin = c->vc_visible_origin;
vgacon_scrollback_cur->save = 0;
if (!vga_is_gfx && !vgacon_scrollback_cur->restore) {
@@ -287,8 +288,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
int start, end, count, soff;
if (!lines) {
- c->vc_visible_origin = c->vc_origin;
- vga_set_mem_top(c);
+ vgacon_restore_screen(c);
@@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
if (!vgacon_scrollback_cur->save) {
vgacon_cursor(c, CM_ERASE);
+ c->vc_origin = (unsigned long)c->vc_screenbuf;
vgacon_scrollback_cur->save = 1;
@@ -335,7 +336,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
int copysize;
int diff = c->vc_rows - count;
- void *d = (void *) c->vc_origin;
+ void *d = (void *) c->vc_visible_origin;
void *s = (void *) c->vc_screenbuf;
count *= c->vc_size_row;