Re: [REVERT Request] VT Breakage

From: Linus Torvalds
Date: Tue Oct 14 2008 - 13:00:00 EST




On Tue, 14 Oct 2008, Alan Cox wrote:
>
> In April someone merged
>
> commit c9e587abfdec2c2aaa55fab83bcb4972e2f84f9b
> Author: Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx>
> Date: Tue Apr 29 00:59:46 2008 -0700
>
> vt: fix background color on line feed
>
>
> Unfortunately it's wrong and its been causing breakages because various
> apps like ncurses expect our previous (and correct) behaviour.
>
> Can you therefore revert it (seems saner than sending you a patch -R)

Actually, you'd need to send a tested patch (or rather, at least test the
trial patch I'm including here). Because it's not a trivial revert at all,
we've had various fbcon fixups since that depend on that commit.

See at least commits

- afa9b649 "fbcon: prevent cursor disappearance after switching to 512
character font"

- d850a2fa "vt/fbcon: fix background color on line feed"

- 7fe3915a "vt/fbcon: update scrl_erase_char after 256/512-glyph font
switch"

and while I suspect that reverting them all in that order (ie

git revert -n afa9b649
git revert -n d850a2fa
git revert -n 7fe3915a
git revert -n c9e587ab

should work (with a trivial fixup), I need somebody to test the result.

Here's the patch as best as I can do. It compiles, but I have not tested
it, nor seen any of the failure cases, so I really don't want to commit it
as-is.

So please check this patch. Also, can somebody please verify what the
_correct_ vt100 behavior is? The test-case was in the original commit, but
quite frankly, it doesn't work on my text console like it does on xterm
_or_ 'termina' for me, _with_ the patch in place. So I suspect a revert is
good, but I want to have this tested/explained more.

Linus

----
drivers/char/vt.c | 7 +++----
drivers/video/console/fbcon.c | 39 ++++++++++-----------------------------
drivers/video/console/mdacon.c | 2 +-
drivers/video/console/sticon.c | 4 ++--
drivers/video/console/vgacon.c | 4 ++--
include/linux/console_struct.h | 1 -
6 files changed, 18 insertions(+), 39 deletions(-)

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 57029fe..4ab5df9 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -301,7 +301,7 @@ static void scrup(struct vc_data *vc, unsigned int t, unsigned int b, int nr)
d = (unsigned short *)(vc->vc_origin + vc->vc_size_row * t);
s = (unsigned short *)(vc->vc_origin + vc->vc_size_row * (t + nr));
scr_memmovew(d, s, (b - t - nr) * vc->vc_size_row);
- scr_memsetw(d + (b - t - nr) * vc->vc_cols, vc->vc_scrl_erase_char,
+ scr_memsetw(d + (b - t - nr) * vc->vc_cols, vc->vc_video_erase_char,
vc->vc_size_row * nr);
}

@@ -319,7 +319,7 @@ static void scrdown(struct vc_data *vc, unsigned int t, unsigned int b, int nr)
s = (unsigned short *)(vc->vc_origin + vc->vc_size_row * t);
step = vc->vc_cols * nr;
scr_memmovew(s + step, s, (b - t - nr) * vc->vc_size_row);
- scr_memsetw(s, vc->vc_scrl_erase_char, 2 * step);
+ scr_memsetw(s, vc->vc_video_erase_char, 2 * step);
}

static void do_update_region(struct vc_data *vc, unsigned long start, int count)
@@ -400,7 +400,7 @@ static u8 build_attr(struct vc_data *vc, u8 _color, u8 _intensity, u8 _blink,
* Bit 7 : blink
*/
{
- u8 a = _color;
+ u8 a = vc->vc_color;
if (!vc->vc_can_do_color)
return _intensity |
(_italic ? 2 : 0) |
@@ -434,7 +434,6 @@ static void update_attr(struct vc_data *vc)
vc->vc_blink, vc->vc_underline,
vc->vc_reverse ^ vc->vc_decscnm, vc->vc_italic);
vc->vc_video_erase_char = (build_attr(vc, vc->vc_color, 1, vc->vc_blink, 0, vc->vc_decscnm, 0) << 8) | ' ';
- vc->vc_scrl_erase_char = (build_attr(vc, vc->vc_def_color, 1, false, false, vc->vc_decscnm, false) << 8) | ' ';
}

/* Note: inverting the screen twice should revert to the original state */
diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 9cbff84..da91bb1 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -1855,8 +1855,6 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
struct display *p = &fb_display[vc->vc_num];
int scroll_partial = info->flags & FBINFO_PARTIAL_PAN_OK;
- unsigned short saved_ec;
- int ret;

if (fbcon_is_inactive(vc, info))
return -EINVAL;
@@ -1869,11 +1867,6 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
* whole screen (prevents flicker).
*/

- saved_ec = vc->vc_video_erase_char;
- vc->vc_video_erase_char = vc->vc_scrl_erase_char;
-
- ret = 0;
-
switch (dir) {
case SM_UP:
if (count > vc->vc_rows) /* Maximum realistic size */
@@ -1890,9 +1883,9 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
scr_memsetw((unsigned short *) (vc->vc_origin +
vc->vc_size_row *
(b - count)),
- vc->vc_scrl_erase_char,
+ vc->vc_video_erase_char,
vc->vc_size_row * count);
- ret = 1;
+ return 1;
break;

case SCROLL_WRAP_MOVE:
@@ -1962,10 +1955,9 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
scr_memsetw((unsigned short *) (vc->vc_origin +
vc->vc_size_row *
(b - count)),
- vc->vc_scrl_erase_char,
+ vc->vc_video_erase_char,
vc->vc_size_row * count);
- ret = 1;
- break;
+ return 1;
}
break;

@@ -1982,9 +1974,9 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
scr_memsetw((unsigned short *) (vc->vc_origin +
vc->vc_size_row *
t),
- vc->vc_scrl_erase_char,
+ vc->vc_video_erase_char,
vc->vc_size_row * count);
- ret = 1;
+ return 1;
break;

case SCROLL_WRAP_MOVE:
@@ -2052,15 +2044,12 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
scr_memsetw((unsigned short *) (vc->vc_origin +
vc->vc_size_row *
t),
- vc->vc_scrl_erase_char,
+ vc->vc_video_erase_char,
vc->vc_size_row * count);
- ret = 1;
- break;
+ return 1;
}
- break;
}
- vc->vc_video_erase_char = saved_ec;
- return ret;
+ return 0;
}


@@ -2522,9 +2511,6 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
c = vc->vc_video_erase_char;
vc->vc_video_erase_char =
((c & 0xfe00) >> 1) | (c & 0xff);
- c = vc->vc_scrl_erase_char;
- vc->vc_scrl_erase_char =
- ((c & 0xFE00) >> 1) | (c & 0xFF);
vc->vc_attr >>= 1;
}
} else if (!vc->vc_hi_font_mask && cnt == 512) {
@@ -2555,14 +2541,9 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
if (vc->vc_can_do_color) {
vc->vc_video_erase_char =
((c & 0xff00) << 1) | (c & 0xff);
- c = vc->vc_scrl_erase_char;
- vc->vc_scrl_erase_char =
- ((c & 0xFF00) << 1) | (c & 0xFF);
vc->vc_attr <<= 1;
- } else {
+ } else
vc->vc_video_erase_char = c & ~0x100;
- vc->vc_scrl_erase_char = c & ~0x100;
- }
}

}
diff --git a/drivers/video/console/mdacon.c b/drivers/video/console/mdacon.c
index 9901064..dd3eaaa 100644
--- a/drivers/video/console/mdacon.c
+++ b/drivers/video/console/mdacon.c
@@ -533,7 +533,7 @@ static void mdacon_cursor(struct vc_data *c, int mode)

static int mdacon_scroll(struct vc_data *c, int t, int b, int dir, int lines)
{
- u16 eattr = mda_convert_attr(c->vc_scrl_erase_char);
+ u16 eattr = mda_convert_attr(c->vc_video_erase_char);

if (!lines)
return 0;
diff --git a/drivers/video/console/sticon.c b/drivers/video/console/sticon.c
index 4055dbd..491c1c1 100644
--- a/drivers/video/console/sticon.c
+++ b/drivers/video/console/sticon.c
@@ -170,12 +170,12 @@ static int sticon_scroll(struct vc_data *conp, int t, int b, int dir, int count)
switch (dir) {
case SM_UP:
sti_bmove(sti, t + count, 0, t, 0, b - t - count, conp->vc_cols);
- sti_clear(sti, b - count, 0, count, conp->vc_cols, conp->vc_scrl_erase_char);
+ sti_clear(sti, b - count, 0, count, conp->vc_cols, conp->vc_video_erase_char);
break;

case SM_DOWN:
sti_bmove(sti, t, 0, t + count, 0, b - t - count, conp->vc_cols);
- sti_clear(sti, t, 0, count, conp->vc_cols, conp->vc_scrl_erase_char);
+ sti_clear(sti, t, 0, count, conp->vc_cols, conp->vc_video_erase_char);
break;
}

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index bd1f57b..6df29a6 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -1350,7 +1350,7 @@ static int vgacon_scroll(struct vc_data *c, int t, int b, int dir,
} else
c->vc_origin += delta;
scr_memsetw((u16 *) (c->vc_origin + c->vc_screenbuf_size -
- delta), c->vc_scrl_erase_char,
+ delta), c->vc_video_erase_char,
delta);
} else {
if (oldo - delta < vga_vram_base) {
@@ -1363,7 +1363,7 @@ static int vgacon_scroll(struct vc_data *c, int t, int b, int dir,
} else
c->vc_origin -= delta;
c->vc_scr_end = c->vc_origin + c->vc_screenbuf_size;
- scr_memsetw((u16 *) (c->vc_origin), c->vc_scrl_erase_char,
+ scr_memsetw((u16 *) (c->vc_origin), c->vc_video_erase_char,
delta);
}
c->vc_scr_end = c->vc_origin + c->vc_screenbuf_size;
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index b03f80a..d71f7c0 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -53,7 +53,6 @@ struct vc_data {
unsigned short vc_hi_font_mask; /* [#] Attribute set for upper 256 chars of font or 0 if not supported */
struct console_font vc_font; /* Current VC font set */
unsigned short vc_video_erase_char; /* Background erase character */
- unsigned short vc_scrl_erase_char; /* Erase character for scroll */
/* VT terminal data */
unsigned int vc_state; /* Escape sequence parser state */
unsigned int vc_npar,vc_par[NPAR]; /* Parameters of current escape sequence */
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