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 <[email protected]>
Cc: [email protected] # 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.
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 09731b2f68..a3353a9970 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);
return;
}
@@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
if (!vgacon_scrollback_cur->save) {
vgacon_cursor(c, CM_ERASE);
vgacon_save_screen(c);
+ c->vc_origin = 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;
On Thu, 10 Jan 2019, Nicolas Pitre wrote:
> 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.
The vt code is just a frigging mess of integer variables and pointer
variables referring to the same thing. It is therefore littered with
casts all over the place. And of course I missed one in this patch.
Here's a revised patch to quiet a warning:
----- >8
Subject: [PATCH] vgacon: unconfuse vc_origin when using soft scrollback
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 <[email protected]>
Cc: [email protected] # 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.
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 09731b2f68..a3353a9970 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);
return;
}
@@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
if (!vgacon_scrollback_cur->save) {
vgacon_cursor(c, CM_ERASE);
vgacon_save_screen(c);
+ c->vc_origin = 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;
On Thu, 10 Jan 2019, Nicolas Pitre wrote:
> The vt code is just a frigging mess of integer variables and pointer
> variables referring to the same thing. It is therefore littered with
> casts all over the place. And of course I missed one in this patch.
>
> Here's a revised patch to quiet a warning:
And of course I forgot to commit and reposted the same patch
with the missing cast. So here it is again:
----- >8
Subject: [PATCH] vgacon: unconfuse vc_origin when using soft scrollback
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 <[email protected]>
Cc: [email protected] # 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.
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 09731b2f68..c6b3bdbbdb 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);
return;
}
@@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
if (!vgacon_scrollback_cur->save) {
vgacon_cursor(c, CM_ERASE);
vgacon_save_screen(c);
+ 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;