vgacon: remove software scrollback support

commit 973c096f6a85e5b5f2a295126ba6928d9a6afd45 upstream.

Yunhai Zhang recently fixed a VGA software scrollback bug in commit
ebfdfeeae8c0 ("vgacon: Fix for missing check in scrollback handling"),
but that then made people look more closely at some of this code, and
there were more problems on the vgacon side, but also the fbcon software
scrollback.

We don't really have anybody who maintains this code - probably because
nobody actually _uses_ it any more.  Sure, people still use both VGA and
the framebuffer consoles, but they are no longer the main user
interfaces to the kernel, and haven't been for decades, so these kinds
of extra features end up bitrotting and not really being used.

So rather than try to maintain a likely unused set of code, I'll just
aggressively remove it, and see if anybody even notices.  Maybe there
are people who haven't jumped on the whole GUI badnwagon yet, and think
it's just a fad.  And maybe those people use the scrollback code.

If that turns out to be the case, we can resurrect this again, once
we've found the sucker^Wmaintainer for it who actually uses it.

Reported-by: NopNop Nop <nopitydays@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Cc: 张云海 <zhangyunhai@nsfocus.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/configs/pasemi_defconfig b/arch/powerpc/configs/pasemi_defconfig
index 76f4edd..07bc4f0 100644 (file)
--- a/arch/powerpc/configs/pasemi_defconfig
+++ b/arch/powerpc/configs/pasemi_defconfig
@@ -115,7 +115,6 @@ CONFIG_FB_NVIDIA=y
 CONFIG_FB_NVIDIA_I2C=y
 CONFIG_FB_RADEON=y
 # CONFIG_LCD_CLASS_DEVICE is not set
-CONFIG_VGACON_SOFT_SCROLLBACK=y
 CONFIG_LOGO=y
 CONFIG_SOUND=y
 CONFIG_SND=y

diff --git a/arch/powerpc/configs/ppc6xx_defconfig b/arch/powerpc/configs/ppc6xx_defconfig
index 8fbf498..1c6815b 100644 (file)
--- a/arch/powerpc/configs/ppc6xx_defconfig
+++ b/arch/powerpc/configs/ppc6xx_defconfig
@@ -796,7 +796,6 @@ CONFIG_FB_TRIDENT=m
 CONFIG_FB_SM501=m
 CONFIG_FB_IBM_GXT4500=y
 CONFIG_LCD_PLATFORM=m
-CONFIG_VGACON_SOFT_SCROLLBACK=y
 CONFIG_FRAMEBUFFER_CONSOLE=y
 CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
 CONFIG_LOGO=y

diff --git a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig
index 5fa6ee2..838dcdc 100644 (file)
--- a/arch/x86/configs/i386_defconfig
+++ b/arch/x86/configs/i386_defconfig
@@ -217,7 +217,6 @@ CONFIG_FB_MODE_HELPERS=y
 CONFIG_FB_TILEBLITTING=y
 CONFIG_FB_EFI=y
 # CONFIG_LCD_CLASS_DEVICE is not set
-CONFIG_VGACON_SOFT_SCROLLBACK=y
 CONFIG_LOGO=y
 # CONFIG_LOGO_LINUX_MONO is not set
 # CONFIG_LOGO_LINUX_VGA16 is not set

diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
index 7ef4a09..7806460 100644 (file)
--- a/arch/x86/configs/x86_64_defconfig
+++ b/arch/x86/configs/x86_64_defconfig
@@ -212,7 +212,6 @@ CONFIG_FB_MODE_HELPERS=y
 CONFIG_FB_TILEBLITTING=y
 CONFIG_FB_EFI=y
 # CONFIG_LCD_CLASS_DEVICE is not set
-CONFIG_VGACON_SOFT_SCROLLBACK=y
 CONFIG_LOGO=y
 # CONFIG_LOGO_LINUX_MONO is not set
 # CONFIG_LOGO_LINUX_VGA16 is not set

diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
index 38da6e2..c317150 100644 (file)
--- a/drivers/video/console/Kconfig
+++ b/drivers/video/console/Kconfig
@@ -22,31 +22,6 @@ config VGA_CONSOLE
 
          Say Y.
 
-config VGACON_SOFT_SCROLLBACK
-       bool "Enable Scrollback Buffer in System RAM"
-       depends on VGA_CONSOLE
-       default n
-       help
-         The scrollback buffer of the standard VGA console is located in
-        the VGA RAM.  The size of this RAM is fixed and is quite small.
-        If you require a larger scrollback buffer, this can be placed in
-        System RAM which is dynamically allocated during initialization.
-        Placing the scrollback buffer in System RAM will slightly slow
-        down the console.
-
-        If you want this feature, say 'Y' here and enter the amount of
-        RAM to allocate for this buffer.  If unsure, say 'N'.
-
-config VGACON_SOFT_SCROLLBACK_SIZE
-       int "Scrollback Buffer Size (in KB)"
-       depends on VGACON_SOFT_SCROLLBACK
-       range 1 1024
-       default "64"
-       help
-         Enter the amount of System RAM to allocate for the scrollback
-        buffer.  Each 64KB will give you approximately 16 80x25
-        screenfuls of scrollback buffer
-
 config MDA_CONSOLE
        depends on !M68K && !PARISC && ISA
        tristate "MDA text console (dual-headed)"

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index d45ba73..b38ee23 100644 (file)
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -179,157 +179,6 @@ static inline void vga_set_mem_top(struct vc_data *c)
        write_vga(12, (c->vc_visible_origin - vga_vram_base) / 2);
 }
 
-#ifdef CONFIG_VGACON_SOFT_SCROLLBACK
-/* software scrollback */
-static void *vgacon_scrollback;
-static int vgacon_scrollback_tail;
-static int vgacon_scrollback_size;
-static int vgacon_scrollback_rows;
-static int vgacon_scrollback_cnt;
-static int vgacon_scrollback_cur;
-static int vgacon_scrollback_save;
-static int vgacon_scrollback_restore;
-
-static void vgacon_scrollback_init(int pitch)
-{
-       int rows = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024/pitch;
-
-       if (vgacon_scrollback) {
-               vgacon_scrollback_cnt  = 0;
-               vgacon_scrollback_tail = 0;
-               vgacon_scrollback_cur  = 0;
-               vgacon_scrollback_rows = rows - 1;
-               vgacon_scrollback_size = rows * pitch;
-       }
-}
-
-static void vgacon_scrollback_startup(void)
-{
-       vgacon_scrollback = kcalloc(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE, 1024, GFP_NOWAIT);
-       vgacon_scrollback_init(vga_video_num_columns * 2);
-}
-
-static void vgacon_scrollback_update(struct vc_data *c, int t, int count)
-{
-       void *p;
-
-       if (!vgacon_scrollback_size || c->vc_num != fg_console)
-               return;
-
-       p = (void *) (c->vc_origin + t * c->vc_size_row);
-
-       while (count--) {
-               if ((vgacon_scrollback_tail + c->vc_size_row) >
-                   vgacon_scrollback_size)
-                       vgacon_scrollback_tail = 0;
-
-               scr_memcpyw(vgacon_scrollback + vgacon_scrollback_tail,
-                           p, c->vc_size_row);
-               vgacon_scrollback_cnt++;
-               p += c->vc_size_row;
-               vgacon_scrollback_tail += c->vc_size_row;
-
-               if (vgacon_scrollback_tail >= vgacon_scrollback_size)
-                       vgacon_scrollback_tail = 0;
-
-               if (vgacon_scrollback_cnt > vgacon_scrollback_rows)
-                       vgacon_scrollback_cnt = vgacon_scrollback_rows;
-
-               vgacon_scrollback_cur = vgacon_scrollback_cnt;
-       }
-}
-
-static void vgacon_restore_screen(struct vc_data *c)
-{
-       vgacon_scrollback_save = 0;
-
-       if (!vga_is_gfx && !vgacon_scrollback_restore) {
-               scr_memcpyw((u16 *) c->vc_origin, (u16 *) c->vc_screenbuf,
-                           c->vc_screenbuf_size > vga_vram_size ?
-                           vga_vram_size : c->vc_screenbuf_size);
-               vgacon_scrollback_restore = 1;
-               vgacon_scrollback_cur = vgacon_scrollback_cnt;
-       }
-}
-
-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);
-               return;
-       }
-
-       if (!vgacon_scrollback)
-               return;
-
-       if (!vgacon_scrollback_save) {
-               vgacon_cursor(c, CM_ERASE);
-               vgacon_save_screen(c);
-               vgacon_scrollback_save = 1;
-       }
-
-       vgacon_scrollback_restore = 0;
-       start = vgacon_scrollback_cur + lines;
-       end = start + abs(lines);
-
-       if (start < 0)
-               start = 0;
-
-       if (start > vgacon_scrollback_cnt)
-               start = vgacon_scrollback_cnt;
-
-       if (end < 0)
-               end = 0;
-
-       if (end > vgacon_scrollback_cnt)
-               end = vgacon_scrollback_cnt;
-
-       vgacon_scrollback_cur = start;
-       count = end - start;
-       soff = vgacon_scrollback_tail - ((vgacon_scrollback_cnt - end) *
-                                        c->vc_size_row);
-       soff -= count * c->vc_size_row;
-
-       if (soff < 0)
-               soff += vgacon_scrollback_size;
-
-       count = vgacon_scrollback_cnt - start;
-
-       if (count > c->vc_rows)
-               count = c->vc_rows;
-
-       if (count) {
-               int copysize;
-
-               int diff = c->vc_rows - count;
-               void *d = (void *) c->vc_origin;
-               void *s = (void *) c->vc_screenbuf;
-
-               count *= c->vc_size_row;
-               /* how much memory to end of buffer left? */
-               copysize = min(count, vgacon_scrollback_size - soff);
-               scr_memcpyw(d, vgacon_scrollback + soff, copysize);
-               d += copysize;
-               count -= copysize;
-
-               if (count) {
-                       scr_memcpyw(d, vgacon_scrollback, count);
-                       d += count;
-               }
-
-               if (diff)
-                       scr_memcpyw(d, s, diff * c->vc_size_row);
-       } else
-               vgacon_cursor(c, CM_MOVE);
-}
-#else
-#define vgacon_scrollback_startup(...) do { } while (0)
-#define vgacon_scrollback_init(...)    do { } while (0)
-#define vgacon_scrollback_update(...)  do { } while (0)
-
 static void vgacon_restore_screen(struct vc_data *c)
 {
        if (c->vc_origin != c->vc_visible_origin)
@@ -365,7 +214,6 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
        }
        vga_set_mem_top(c);
 }
-#endif /* CONFIG_VGACON_SOFT_SCROLLBACK */
 
 static const char *vgacon_startup(void)
 {
@@ -562,10 +410,7 @@ static const char *vgacon_startup(void)
        vgacon_xres = screen_info.orig_video_cols * VGA_FONTWIDTH;
        vgacon_yres = vga_scan_lines;
 
-       if (!vga_init_done) {
-               vgacon_scrollback_startup();
-               vga_init_done = 1;
-       }
+       vga_init_done = 1;
 
        return display_desc;
 }
@@ -861,7 +706,6 @@ static int vgacon_switch(struct vc_data *c)
                        vgacon_doresize(c, c->vc_cols, c->vc_rows);
        }
 
-       vgacon_scrollback_init(c->vc_size_row);
        return 0;               /* Redrawing not needed */
 }
 
@@ -1391,7 +1235,6 @@ static int vgacon_scroll(struct vc_data *c, int t, int b, int dir,
        oldo = c->vc_origin;
        delta = lines * c->vc_size_row;
        if (dir == SM_UP) {
-               vgacon_scrollback_update(c, t, lines);
                if (c->vc_scr_end + delta >= vga_vram_end) {
                        scr_memcpyw((u16 *) vga_vram_base,
                                    (u16 *) (oldo + delta),