From 7cabb35d2106d567af15ea1040c7737f34b29cd8 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 9 Sep 2020 14:53:50 -0700 Subject: [PATCH] vgacon: remove software scrollback support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Tested-by: Willy Tarreau Cc: 张云海 Acked-by: Andy Lutomirski Acked-by: Willy Tarreau Reviewed-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/configs/pasemi_defconfig | 1 - arch/powerpc/configs/ppc6xx_defconfig | 1 - arch/x86/configs/i386_defconfig | 1 - arch/x86/configs/x86_64_defconfig | 1 - drivers/video/console/Kconfig | 25 ---- drivers/video/console/vgacon.c | 159 +------------------------- 6 files changed, 1 insertion(+), 187 deletions(-) diff --git a/arch/powerpc/configs/pasemi_defconfig b/arch/powerpc/configs/pasemi_defconfig index 76f4edd441d3..07bc4f038249 100644 --- 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 8fbf49801233..1c6815bcc616 100644 --- 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 5fa6ee2c2dde..838dcdc39568 100644 --- 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 7ef4a099defc..7806460b1bb8 100644 --- 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 38da6e299149..c31715019cb4 100644 --- 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 d45ba7317b22..b38ee2354cbf 100644 --- 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),