From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001
From: Zeng Chi <zengchi@kylinos.cn>
Date: Mon, 21 Sep 2026 18:24:42 +0800
Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL
 attributes

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 drivers/video/console/vgacon.c | 1226 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 1226 insertions(+)
 create mode 100644 drivers/video/console/vgacon.c

(limited to 'drivers/video/console/vgacon.c')

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
new file mode 100644
index 000000000..37bd18730
--- /dev/null
+++ b/drivers/video/console/vgacon.c
@@ -0,0 +1,1226 @@
+/*
+ *  linux/drivers/video/vgacon.c -- Low level VGA based console driver
+ *
+ *	Created 28 Sep 1997 by Geert Uytterhoeven
+ *
+ *	Rewritten by Martin Mares <mj@ucw.cz>, July 1998
+ *
+ *  This file is based on the old console.c, vga.c and vesa_blank.c drivers.
+ *
+ *	Copyright (C) 1991, 1992  Linus Torvalds
+ *			    1995  Jay Estabrook
+ *
+ *	User definable mapping table and font loading by Eugene G. Crosser,
+ *	<crosser@average.org>
+ *
+ *	Improved loadable font/UTF-8 support by H. Peter Anvin
+ *	Feb-Sep 1995 <peter.anvin@linux.org>
+ *
+ *	Colour palette handling, by Simon Tatham
+ *	17-Jun-95 <sgt20@cam.ac.uk>
+ *
+ *	if 512 char mode is already enabled don't re-enable it,
+ *	because it causes screen to flicker, by Mitja Horvat
+ *	5-May-96 <mitja.horvat@guest.arnes.si>
+ *
+ *	Use 2 outw instead of 4 outb_p to reduce erroneous text
+ *	flashing on RHS of screen during heavy console scrolling .
+ *	Oct 1996, Paul Gortmaker.
+ *
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License.  See the file COPYING in the main directory of this archive for
+ *  more details.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/console.h>
+#include <linux/string.h>
+#include <linux/kd.h>
+#include <linux/slab.h>
+#include <linux/vt_kern.h>
+#include <linux/sched.h>
+#include <linux/selection.h>
+#include <linux/spinlock.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/screen_info.h>
+#include <video/vga.h>
+#include <asm/io.h>
+
+static DEFINE_RAW_SPINLOCK(vga_lock);
+static int cursor_size_lastfrom;
+static int cursor_size_lastto;
+static u32 vgacon_xres;
+static u32 vgacon_yres;
+static struct vgastate vgastate;
+
+#define BLANK 0x0020
+
+#define VGA_FONTWIDTH       8   /* VGA does not support fontwidths != 8 */
+/*
+ *  Interface used by the world
+ */
+
+static bool vgacon_set_origin(struct vc_data *c);
+
+static struct uni_pagedict *vgacon_uni_pagedir;
+static int vgacon_refcount;
+
+/* Description of the hardware situation */
+static unsigned long	vga_vram_base		__read_mostly;	/* Base of video memory */
+static unsigned long	vga_vram_end		__read_mostly;	/* End of video memory */
+static unsigned int	vga_vram_size		__read_mostly;	/* Size of video memory */
+static u16		vga_video_port_reg	__read_mostly;	/* Video register select port */
+static u16		vga_video_port_val	__read_mostly;	/* Video register value port */
+static unsigned int	vga_video_num_columns;			/* Number of text columns */
+static unsigned int	vga_video_num_lines;			/* Number of text lines */
+static bool		vga_can_do_color;			/* Do we support colors? */
+static unsigned int	vga_default_font_height __read_mostly;	/* Height of default screen font */
+static unsigned char	vga_video_type		__read_mostly;	/* Card type */
+static enum vesa_blank_mode vga_vesa_blanked;
+static bool 		vga_palette_blanked;
+static bool 		vga_is_gfx;
+static bool 		vga_512_chars;
+static int 		vga_video_font_height;
+static int 		vga_scan_lines		__read_mostly;
+static unsigned int 	vga_rolled_over; /* last vc_origin offset before wrap */
+
+static struct screen_info *vga_si;
+
+static bool vga_hardscroll_enabled;
+static bool vga_hardscroll_user_enable = true;
+
+static int __init no_scroll(char *str)
+{
+	/*
+	 * Disabling scrollback is required for the Braillex ib80-piezo
+	 * Braille reader made by F.H. Papenmeier (Germany).
+	 * Use the "no-scroll" bootflag.
+	 */
+	vga_hardscroll_user_enable = vga_hardscroll_enabled = false;
+	return 1;
+}
+
+__setup("no-scroll", no_scroll);
+
+/*
+ * By replacing the four outb_p with two back to back outw, we can reduce
+ * the window of opportunity to see text mislocated to the RHS of the
+ * console during heavy scrolling activity. However there is the remote
+ * possibility that some pre-dinosaur hardware won't like the back to back
+ * I/O. Since the Xservers get away with it, we should be able to as well.
+ */
+static inline void write_vga(unsigned char reg, unsigned int val)
+{
+	unsigned int v1, v2;
+	unsigned long flags;
+
+	/*
+	 * ddprintk might set the console position from interrupt
+	 * handlers, thus the write has to be IRQ-atomic.
+	 */
+	raw_spin_lock_irqsave(&vga_lock, flags);
+	v1 = reg + (val & 0xff00);
+	v2 = reg + 1 + ((val << 8) & 0xff00);
+	outw(v1, vga_video_port_reg);
+	outw(v2, vga_video_port_reg);
+	raw_spin_unlock_irqrestore(&vga_lock, flags);
+}
+
+static inline void vga_set_mem_top(struct vc_data *c)
+{
+	write_vga(12, (c->vc_visible_origin - vga_vram_base) / 2);
+}
+
+static void vgacon_scrolldelta(struct vc_data *c, int lines)
+{
+	unsigned long scr_end = c->vc_scr_end - vga_vram_base;
+	unsigned long vorigin = c->vc_visible_origin - vga_vram_base;
+	unsigned long origin = c->vc_origin - vga_vram_base;
+	int margin = c->vc_size_row * 4;
+	int from, wrap, from_off, avail;
+
+	/* Turn scrollback off */
+	if (!lines) {
+		c->vc_visible_origin = c->vc_origin;
+		return;
+	}
+
+	/* Do we have already enough to allow jumping from 0 to the end? */
+	if (vga_rolled_over > scr_end + margin) {
+		from = scr_end;
+		wrap = vga_rolled_over + c->vc_size_row;
+	} else {
+		from = 0;
+		wrap = vga_vram_size;
+	}
+
+	from_off = (vorigin - from + wrap) % wrap + lines * c->vc_size_row;
+	avail = (origin - from + wrap) % wrap;
+
+	/* Only a little piece would be left? Show all incl. the piece! */
+	if (avail < 2 * margin)
+		margin = 0;
+	if (from_off < margin)
+		from_off = 0;
+	if (from_off > avail - margin)
+		from_off = avail;
+
+	c->vc_visible_origin = vga_vram_base + (from + from_off) % wrap;
+
+	vga_set_mem_top(c);
+}
+
+static void vgacon_restore_screen(struct vc_data *c)
+{
+	if (c->vc_origin != c->vc_visible_origin)
+		vgacon_scrolldelta(c, 0);
+}
+
+static const char *vgacon_startup(void)
+{
+	const char *display_desc = NULL;
+	u16 saved1, saved2;
+	volatile u16 *p;
+
+	if (!vga_si ||
+	    vga_si->orig_video_isVGA == VIDEO_TYPE_VLFB ||
+	    vga_si->orig_video_isVGA == VIDEO_TYPE_EFI) {
+	      no_vga:
+#ifdef CONFIG_DUMMY_CONSOLE
+		conswitchp = &dummy_con;
+		return conswitchp->con_startup();
+#else
+		return NULL;
+#endif
+	}
+
+	/* vga_si reasonably initialized? */
+	if ((vga_si->orig_video_lines == 0) ||
+	    (vga_si->orig_video_cols  == 0))
+		goto no_vga;
+
+	/* VGA16 modes are not handled by VGACON */
+	if ((vga_si->orig_video_mode == 0x0D) ||	/* 320x200/4 */
+	    (vga_si->orig_video_mode == 0x0E) ||	/* 640x200/4 */
+	    (vga_si->orig_video_mode == 0x10) ||	/* 640x350/4 */
+	    (vga_si->orig_video_mode == 0x12) ||	/* 640x480/4 */
+	    (vga_si->orig_video_mode == 0x6A))	/* 800x600/4 (VESA) */
+		goto no_vga;
+
+	vga_video_num_lines = vga_si->orig_video_lines;
+	vga_video_num_columns = vga_si->orig_video_cols;
+	vgastate.vgabase = NULL;
+
+	if (vga_si->orig_video_mode == 7) {
+		/* Monochrome display */
+		vga_vram_base = 0xb0000;
+		vga_video_port_reg = VGA_CRT_IM;
+		vga_video_port_val = VGA_CRT_DM;
+		if ((vga_si->orig_video_ega_bx & 0xff) != 0x10) {
+			static struct resource ega_console_resource =
+			    { .name	= "ega",
+			      .flags	= IORESOURCE_IO,
+			      .start	= 0x3B0,
+			      .end	= 0x3BF };
+			vga_video_type = VIDEO_TYPE_EGAM;
+			vga_vram_size = 0x8000;
+			display_desc = "EGA+";
+			request_resource(&ioport_resource,
+					 &ega_console_resource);
+		} else {
+			static struct resource mda1_console_resource =
+			    { .name	= "mda",
+			      .flags	= IORESOURCE_IO,
+			      .start	= 0x3B0,
+			      .end	= 0x3BB };
+			static struct resource mda2_console_resource =
+			    { .name	= "mda",
+			      .flags	= IORESOURCE_IO,
+			      .start	= 0x3BF,
+			      .end	= 0x3BF };
+			vga_video_type = VIDEO_TYPE_MDA;
+			vga_vram_size = 0x2000;
+			display_desc = "*MDA";
+			request_resource(&ioport_resource,
+					 &mda1_console_resource);
+			request_resource(&ioport_resource,
+					 &mda2_console_resource);
+			vga_video_font_height = 14;
+		}
+	} else {
+		/* If not, it is color. */
+		vga_can_do_color = true;
+		vga_vram_base = 0xb8000;
+		vga_video_port_reg = VGA_CRT_IC;
+		vga_video_port_val = VGA_CRT_DC;
+		if ((vga_si->orig_video_ega_bx & 0xff) != 0x10) {
+			int i;
+
+			vga_vram_size = 0x8000;
+
+			if (!vga_si->orig_video_isVGA) {
+				static struct resource ega_console_resource =
+				    { .name	= "ega",
+				      .flags	= IORESOURCE_IO,
+				      .start	= 0x3C0,
+				      .end	= 0x3DF };
+				vga_video_type = VIDEO_TYPE_EGAC;
+				display_desc = "EGA";
+				request_resource(&ioport_resource,
+						 &ega_console_resource);
+			} else {
+				static struct resource vga_console_resource =
+				    { .name	= "vga+",
+				      .flags	= IORESOURCE_IO,
+				      .start	= 0x3C0,
+				      .end	= 0x3DF };
+				vga_video_type = VIDEO_TYPE_VGAC;
+				display_desc = "VGA+";
+				request_resource(&ioport_resource,
+						 &vga_console_resource);
+
+				/*
+				 * Normalise the palette registers, to point
+				 * the 16 screen colours to the first 16
+				 * DAC entries.
+				 */
+
+				for (i = 0; i < 16; i++) {
+					inb_p(VGA_IS1_RC);
+					outb_p(i, VGA_ATT_W);
+					outb_p(i, VGA_ATT_W);
+				}
+				outb_p(0x20, VGA_ATT_W);
+
+				/*
+				 * Now set the DAC registers back to their
+				 * default values
+				 */
+				for (i = 0; i < 16; i++) {
+					outb_p(color_table[i], VGA_PEL_IW);
+					outb_p(default_red[i], VGA_PEL_D);
+					outb_p(default_grn[i], VGA_PEL_D);
+					outb_p(default_blu[i], VGA_PEL_D);
+				}
+			}
+		} else {
+			static struct resource cga_console_resource =
+			    { .name	= "cga",
+			      .flags	= IORESOURCE_IO,
+			      .start	= 0x3D4,
+			      .end	= 0x3D5 };
+			vga_video_type = VIDEO_TYPE_CGA;
+			vga_vram_size = 0x2000;
+			display_desc = "*CGA";
+			request_resource(&ioport_resource,
+					 &cga_console_resource);
+			vga_video_font_height = 8;
+		}
+	}
+
+	vga_vram_base = VGA_MAP_MEM(vga_vram_base, vga_vram_size);
+	vga_vram_end = vga_vram_base + vga_vram_size;
+
+	/*
+	 *      Find out if there is a graphics card present.
+	 *      Are there smarter methods around?
+	 */
+	p = (volatile u16 *) vga_vram_base;
+	saved1 = scr_readw(p);
+	saved2 = scr_readw(p + 1);
+	scr_writew(0xAA55, p);
+	scr_writew(0x55AA, p + 1);
+	if (scr_readw(p) != 0xAA55 || scr_readw(p + 1) != 0x55AA) {
+		scr_writew(saved1, p);
+		scr_writew(saved2, p + 1);
+		goto no_vga;
+	}
+	scr_writew(0x55AA, p);
+	scr_writew(0xAA55, p + 1);
+	if (scr_readw(p) != 0x55AA || scr_readw(p + 1) != 0xAA55) {
+		scr_writew(saved1, p);
+		scr_writew(saved2, p + 1);
+		goto no_vga;
+	}
+	scr_writew(saved1, p);
+	scr_writew(saved2, p + 1);
+
+	if (vga_video_type == VIDEO_TYPE_EGAC
+	    || vga_video_type == VIDEO_TYPE_VGAC
+	    || vga_video_type == VIDEO_TYPE_EGAM) {
+		vga_hardscroll_enabled = vga_hardscroll_user_enable;
+		vga_default_font_height = vga_si->orig_video_points;
+		vga_video_font_height = vga_si->orig_video_points;
+		/* This may be suboptimal but is a safe bet - go with it */
+		vga_scan_lines =
+		    vga_video_font_height * vga_video_num_lines;
+	}
+
+	vgacon_xres = vga_si->orig_video_cols * VGA_FONTWIDTH;
+	vgacon_yres = vga_scan_lines;
+
+	return display_desc;
+}
+
+static void vgacon_init(struct vc_data *c, bool init)
+{
+	struct uni_pagedict *p;
+
+	/*
+	 * We cannot be loaded as a module, therefore init will be 1
+	 * if we are the default console, however if we are a fallback
+	 * console, for example if fbcon has failed registration, then
+	 * init will be 0, so we need to make sure our boot parameters
+	 * have been copied to the console structure for vgacon_resize
+	 * ultimately called by vc_resize.  Any subsequent calls to
+	 * vgacon_init init will have init set to 0 too.
+	 */
+	c->vc_can_do_color = vga_can_do_color;
+	c->vc_scan_lines = vga_scan_lines;
+	c->vc_font.height = c->vc_cell_height = vga_video_font_height;
+
+	/* set dimensions manually if init is true since vc_resize() will fail */
+	if (init) {
+		c->vc_cols = vga_video_num_columns;
+		c->vc_rows = vga_video_num_lines;
+	} else
+		vc_resize(c, vga_video_num_columns, vga_video_num_lines);
+
+	c->vc_complement_mask = 0x7700;
+	if (vga_512_chars)
+		c->vc_hi_font_mask = 0x0800;
+	p = *c->uni_pagedict_loc;
+	if (c->uni_pagedict_loc != &vgacon_uni_pagedir) {
+		con_free_unimap(c);
+		c->uni_pagedict_loc = &vgacon_uni_pagedir;
+		vgacon_refcount++;
+	}
+	if (!vgacon_uni_pagedir && p)
+		con_set_default_unimap(c);
+
+	/* Only set the default if the user didn't deliberately override it */
+	if (global_cursor_default == -1)
+		global_cursor_default =
+			!(vga_si->flags & VIDEO_FLAGS_NOCURSOR);
+}
+
+static void vgacon_deinit(struct vc_data *c)
+{
+	/* When closing the active console, reset video origin */
+	if (con_is_visible(c)) {
+		c->vc_visible_origin = vga_vram_base;
+		vga_set_mem_top(c);
+	}
+
+	if (!--vgacon_refcount)
+		con_free_unimap(c);
+	c->uni_pagedict_loc = &c->uni_pagedict;
+	con_set_default_unimap(c);
+}
+
+static u8 vgacon_build_attr(struct vc_data *c, u8 color,
+			    enum vc_intensity intensity,
+			    bool blink, bool underline, bool reverse,
+			    bool italic)
+{
+	u8 attr = color;
+
+	if (vga_can_do_color) {
+		if (italic)
+			attr = (attr & 0xF0) | c->vc_itcolor;
+		else if (underline)
+			attr = (attr & 0xf0) | c->vc_ulcolor;
+		else if (intensity == VCI_HALF_BRIGHT)
+			attr = (attr & 0xf0) | c->vc_halfcolor;
+	}
+	if (reverse)
+		attr =
+		    ((attr) & 0x88) | ((((attr) >> 4) | ((attr) << 4)) &
+				       0x77);
+	if (blink)
+		attr ^= 0x80;
+	if (intensity == VCI_BOLD)
+		attr ^= 0x08;
+	if (!vga_can_do_color) {
+		if (italic)
+			attr = (attr & 0xF8) | 0x02;
+		else if (underline)
+			attr = (attr & 0xf8) | 0x01;
+		else if (intensity == VCI_HALF_BRIGHT)
+			attr = (attr & 0xf0) | 0x08;
+	}
+	return attr;
+}
+
+static void vgacon_invert_region(struct vc_data *c, u16 * p, int count)
+{
+	const bool col = vga_can_do_color;
+
+	while (count--) {
+		u16 a = scr_readw(p);
+		if (col)
+			a = ((a) & 0x88ff) | (((a) & 0x7000) >> 4) |
+			    (((a) & 0x0700) << 4);
+		else
+			a ^= ((a & 0x0700) == 0x0100) ? 0x7000 : 0x7700;
+		scr_writew(a, p++);
+	}
+}
+
+static void vgacon_set_cursor_size(int from, int to)
+{
+	unsigned long flags;
+	int curs, cure;
+
+	if ((from == cursor_size_lastfrom) && (to == cursor_size_lastto))
+		return;
+	cursor_size_lastfrom = from;
+	cursor_size_lastto = to;
+
+	raw_spin_lock_irqsave(&vga_lock, flags);
+	if (vga_video_type >= VIDEO_TYPE_VGAC) {
+		outb_p(VGA_CRTC_CURSOR_START, vga_video_port_reg);
+		curs = inb_p(vga_video_port_val);
+		outb_p(VGA_CRTC_CURSOR_END, vga_video_port_reg);
+		cure = inb_p(vga_video_port_val);
+	} else {
+		curs = 0;
+		cure = 0;
+	}
+
+	curs = (curs & 0xc0) | from;
+	cure = (cure & 0xe0) | to;
+
+	outb_p(VGA_CRTC_CURSOR_START, vga_video_port_reg);
+	outb_p(curs, vga_video_port_val);
+	outb_p(VGA_CRTC_CURSOR_END, vga_video_port_reg);
+	outb_p(cure, vga_video_port_val);
+	raw_spin_unlock_irqrestore(&vga_lock, flags);
+}
+
+static void vgacon_cursor(struct vc_data *c, bool enable)
+{
+	unsigned int c_height;
+
+	if (c->vc_mode != KD_TEXT)
+		return;
+
+	vgacon_restore_screen(c);
+
+	c_height = c->vc_cell_height;
+
+	write_vga(14, (c->vc_pos - vga_vram_base) / 2);
+
+	if (!enable) {
+	        if (vga_video_type >= VIDEO_TYPE_VGAC)
+			vgacon_set_cursor_size(31, 30);
+		else
+			vgacon_set_cursor_size(31, 31);
+		return;
+	}
+
+	switch (CUR_SIZE(c->vc_cursor_type)) {
+	case CUR_UNDERLINE:
+		vgacon_set_cursor_size(c_height - (c_height < 10 ? 2 : 3),
+				       c_height - (c_height < 10 ? 1 : 2));
+		break;
+	case CUR_TWO_THIRDS:
+		vgacon_set_cursor_size(c_height / 3,
+				       c_height - (c_height < 10 ? 1 : 2));
+		break;
+	case CUR_LOWER_THIRD:
+		vgacon_set_cursor_size(c_height * 2 / 3,
+				       c_height - (c_height < 10 ? 1 : 2));
+		break;
+	case CUR_LOWER_HALF:
+		vgacon_set_cursor_size(c_height / 2,
+				       c_height - (c_height < 10 ? 1 : 2));
+		break;
+	case CUR_NONE:
+		if (vga_video_type >= VIDEO_TYPE_VGAC)
+			vgacon_set_cursor_size(31, 30);
+		else
+			vgacon_set_cursor_size(31, 31);
+		break;
+	default:
+		vgacon_set_cursor_size(1, c_height);
+		break;
+	}
+}
+
+static void vgacon_doresize(struct vc_data *c,
+		unsigned int width, unsigned int height)
+{
+	unsigned long flags;
+	unsigned int scanlines = height * c->vc_cell_height;
+	u8 scanlines_lo = 0, r7 = 0, vsync_end = 0, mode, max_scan;
+
+	raw_spin_lock_irqsave(&vga_lock, flags);
+
+	vgacon_xres = width * VGA_FONTWIDTH;
+	vgacon_yres = height * c->vc_cell_height;
+	if (vga_video_type >= VIDEO_TYPE_VGAC) {
+		outb_p(VGA_CRTC_MAX_SCAN, vga_video_port_reg);
+		max_scan = inb_p(vga_video_port_val);
+
+		if (max_scan & 0x80)
+			scanlines <<= 1;
+
+		outb_p(VGA_CRTC_MODE, vga_video_port_reg);
+		mode = inb_p(vga_video_port_val);
+
+		if (mode & 0x04)
+			scanlines >>= 1;
+
+		scanlines -= 1;
+		scanlines_lo = scanlines & 0xff;
+
+		outb_p(VGA_CRTC_OVERFLOW, vga_video_port_reg);
+		r7 = inb_p(vga_video_port_val) & ~0x42;
+
+		if (scanlines & 0x100)
+			r7 |= 0x02;
+		if (scanlines & 0x200)
+			r7 |= 0x40;
+
+		/* deprotect registers */
+		outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
+		vsync_end = inb_p(vga_video_port_val);
+		outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
+		outb_p(vsync_end & ~0x80, vga_video_port_val);
+	}
+
+	outb_p(VGA_CRTC_H_DISP, vga_video_port_reg);
+	outb_p(width - 1, vga_video_port_val);
+	outb_p(VGA_CRTC_OFFSET, vga_video_port_reg);
+	outb_p(width >> 1, vga_video_port_val);
+
+	if (vga_video_type >= VIDEO_TYPE_VGAC) {
+		outb_p(VGA_CRTC_V_DISP_END, vga_video_port_reg);
+		outb_p(scanlines_lo, vga_video_port_val);
+		outb_p(VGA_CRTC_OVERFLOW, vga_video_port_reg);
+		outb_p(r7,vga_video_port_val);
+
+		/* reprotect registers */
+		outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
+		outb_p(vsync_end, vga_video_port_val);
+	}
+
+	raw_spin_unlock_irqrestore(&vga_lock, flags);
+}
+
+static bool vgacon_switch(struct vc_data *c)
+{
+	int x = c->vc_cols * VGA_FONTWIDTH;
+	int y = c->vc_rows * c->vc_cell_height;
+	int rows = vga_si->orig_video_lines * vga_default_font_height/
+		c->vc_cell_height;
+	/*
+	 * We need to save screen size here as it's the only way
+	 * we can spot the screen has been resized and we need to
+	 * set size of freshly allocated screens ourselves.
+	 */
+	vga_video_num_columns = c->vc_cols;
+	vga_video_num_lines = c->vc_rows;
+
+	/* We can only copy out the size of the video buffer here,
+	 * otherwise we get into VGA BIOS */
+
+	if (!vga_is_gfx) {
+		scr_memcpyw((u16 *) c->vc_origin, (u16 *) c->vc_screenbuf,
+			    c->vc_screenbuf_size > vga_vram_size ?
+				vga_vram_size : c->vc_screenbuf_size);
+
+		if ((vgacon_xres != x || vgacon_yres != y) &&
+		    (!(vga_video_num_columns % 2) &&
+		     vga_video_num_columns <= vga_si->orig_video_cols &&
+		     vga_video_num_lines <= rows))
+			vgacon_doresize(c, c->vc_cols, c->vc_rows);
+	}
+
+	return false;		/* Redrawing not needed */
+}
+
+static void vga_set_palette(struct vc_data *vc, const unsigned char *table)
+{
+	int i, j;
+
+	vga_w(vgastate.vgabase, VGA_PEL_MSK, 0xff);
+	for (i = j = 0; i < 16; i++) {
+		vga_w(vgastate.vgabase, VGA_PEL_IW, table[i]);
+		vga_w(vgastate.vgabase, VGA_PEL_D, vc->vc_palette[j++] >> 2);
+		vga_w(vgastate.vgabase, VGA_PEL_D, vc->vc_palette[j++] >> 2);
+		vga_w(vgastate.vgabase, VGA_PEL_D, vc->vc_palette[j++] >> 2);
+	}
+}
+
+static void vgacon_set_palette(struct vc_data *vc, const unsigned char *table)
+{
+	if (vga_video_type != VIDEO_TYPE_VGAC || vga_palette_blanked
+	    || !con_is_visible(vc))
+		return;
+	vga_set_palette(vc, table);
+}
+
+/* structure holding original VGA register settings */
+static struct {
+	unsigned char SeqCtrlIndex;	/* Sequencer Index reg.   */
+	unsigned char CrtCtrlIndex;	/* CRT-Contr. Index reg.  */
+	unsigned char CrtMiscIO;	/* Miscellaneous register */
+	unsigned char HorizontalTotal;	/* CRT-Controller:00h */
+	unsigned char HorizDisplayEnd;	/* CRT-Controller:01h */
+	unsigned char StartHorizRetrace;	/* CRT-Controller:04h */
+	unsigned char EndHorizRetrace;	/* CRT-Controller:05h */
+	unsigned char Overflow;	/* CRT-Controller:07h */
+	unsigned char StartVertRetrace;	/* CRT-Controller:10h */
+	unsigned char EndVertRetrace;	/* CRT-Controller:11h */
+	unsigned char ModeControl;	/* CRT-Controller:17h */
+	unsigned char ClockingMode;	/* Seq-Controller:01h */
+} vga_state;
+
+static void vga_vesa_blank(struct vgastate *state, enum vesa_blank_mode mode)
+{
+	/* save original values of VGA controller registers */
+	if (!vga_vesa_blanked) {
+		raw_spin_lock_irq(&vga_lock);
+		vga_state.SeqCtrlIndex = vga_r(state->vgabase, VGA_SEQ_I);
+		vga_state.CrtCtrlIndex = inb_p(vga_video_port_reg);
+		vga_state.CrtMiscIO = vga_r(state->vgabase, VGA_MIS_R);
+		raw_spin_unlock_irq(&vga_lock);
+
+		outb_p(0x00, vga_video_port_reg);	/* HorizontalTotal */
+		vga_state.HorizontalTotal = inb_p(vga_video_port_val);
+		outb_p(0x01, vga_video_port_reg);	/* HorizDisplayEnd */
+		vga_state.HorizDisplayEnd = inb_p(vga_video_port_val);
+		outb_p(0x04, vga_video_port_reg);	/* StartHorizRetrace */
+		vga_state.StartHorizRetrace = inb_p(vga_video_port_val);
+		outb_p(0x05, vga_video_port_reg);	/* EndHorizRetrace */
+		vga_state.EndHorizRetrace = inb_p(vga_video_port_val);
+		outb_p(0x07, vga_video_port_reg);	/* Overflow */
+		vga_state.Overflow = inb_p(vga_video_port_val);
+		outb_p(0x10, vga_video_port_reg);	/* StartVertRetrace */
+		vga_state.StartVertRetrace = inb_p(vga_video_port_val);
+		outb_p(0x11, vga_video_port_reg);	/* EndVertRetrace */
+		vga_state.EndVertRetrace = inb_p(vga_video_port_val);
+		outb_p(0x17, vga_video_port_reg);	/* ModeControl */
+		vga_state.ModeControl = inb_p(vga_video_port_val);
+		vga_state.ClockingMode = vga_rseq(state->vgabase, VGA_SEQ_CLOCK_MODE);
+	}
+
+	/* assure that video is enabled */
+	/* "0x20" is VIDEO_ENABLE_bit in register 01 of sequencer */
+	raw_spin_lock_irq(&vga_lock);
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, vga_state.ClockingMode | 0x20);
+
+	/* test for vertical retrace in process.... */
+	if ((vga_state.CrtMiscIO & 0x80) == 0x80)
+		vga_w(state->vgabase, VGA_MIS_W, vga_state.CrtMiscIO & 0xEF);
+
+	/*
+	 * Set <End of vertical retrace> to minimum (0) and
+	 * <Start of vertical Retrace> to maximum (incl. overflow)
+	 * Result: turn off vertical sync (VSync) pulse.
+	 */
+	if (mode & VESA_VSYNC_SUSPEND) {
+		outb_p(0x10, vga_video_port_reg);	/* StartVertRetrace */
+		outb_p(0xff, vga_video_port_val);	/* maximum value */
+		outb_p(0x11, vga_video_port_reg);	/* EndVertRetrace */
+		outb_p(0x40, vga_video_port_val);	/* minimum (bits 0..3)  */
+		outb_p(0x07, vga_video_port_reg);	/* Overflow */
+		outb_p(vga_state.Overflow | 0x84, vga_video_port_val);	/* bits 9,10 of vert. retrace */
+	}
+
+	if (mode & VESA_HSYNC_SUSPEND) {
+		/*
+		 * Set <End of horizontal retrace> to minimum (0) and
+		 *  <Start of horizontal Retrace> to maximum
+		 * Result: turn off horizontal sync (HSync) pulse.
+		 */
+		outb_p(0x04, vga_video_port_reg);	/* StartHorizRetrace */
+		outb_p(0xff, vga_video_port_val);	/* maximum */
+		outb_p(0x05, vga_video_port_reg);	/* EndHorizRetrace */
+		outb_p(0x00, vga_video_port_val);	/* minimum (0) */
+	}
+
+	/* restore both index registers */
+	vga_w(state->vgabase, VGA_SEQ_I, vga_state.SeqCtrlIndex);
+	outb_p(vga_state.CrtCtrlIndex, vga_video_port_reg);
+	raw_spin_unlock_irq(&vga_lock);
+}
+
+static void vga_vesa_unblank(struct vgastate *state)
+{
+	/* restore original values of VGA controller registers */
+	raw_spin_lock_irq(&vga_lock);
+	vga_w(state->vgabase, VGA_MIS_W, vga_state.CrtMiscIO);
+
+	outb_p(0x00, vga_video_port_reg);	/* HorizontalTotal */
+	outb_p(vga_state.HorizontalTotal, vga_video_port_val);
+	outb_p(0x01, vga_video_port_reg);	/* HorizDisplayEnd */
+	outb_p(vga_state.HorizDisplayEnd, vga_video_port_val);
+	outb_p(0x04, vga_video_port_reg);	/* StartHorizRetrace */
+	outb_p(vga_state.StartHorizRetrace, vga_video_port_val);
+	outb_p(0x05, vga_video_port_reg);	/* EndHorizRetrace */
+	outb_p(vga_state.EndHorizRetrace, vga_video_port_val);
+	outb_p(0x07, vga_video_port_reg);	/* Overflow */
+	outb_p(vga_state.Overflow, vga_video_port_val);
+	outb_p(0x10, vga_video_port_reg);	/* StartVertRetrace */
+	outb_p(vga_state.StartVertRetrace, vga_video_port_val);
+	outb_p(0x11, vga_video_port_reg);	/* EndVertRetrace */
+	outb_p(vga_state.EndVertRetrace, vga_video_port_val);
+	outb_p(0x17, vga_video_port_reg);	/* ModeControl */
+	outb_p(vga_state.ModeControl, vga_video_port_val);
+	/* ClockingMode */
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, vga_state.ClockingMode);
+
+	/* restore index/control registers */
+	vga_w(state->vgabase, VGA_SEQ_I, vga_state.SeqCtrlIndex);
+	outb_p(vga_state.CrtCtrlIndex, vga_video_port_reg);
+	raw_spin_unlock_irq(&vga_lock);
+}
+
+static void vga_pal_blank(struct vgastate *state)
+{
+	int i;
+
+	vga_w(state->vgabase, VGA_PEL_MSK, 0xff);
+	for (i = 0; i < 16; i++) {
+		vga_w(state->vgabase, VGA_PEL_IW, i);
+		vga_w(state->vgabase, VGA_PEL_D, 0);
+		vga_w(state->vgabase, VGA_PEL_D, 0);
+		vga_w(state->vgabase, VGA_PEL_D, 0);
+	}
+}
+
+static bool vgacon_blank(struct vc_data *c, enum vesa_blank_mode blank,
+			 bool mode_switch)
+{
+	switch (blank) {
+	case VESA_NO_BLANKING:		/* Unblank */
+		if (vga_vesa_blanked) {
+			vga_vesa_unblank(&vgastate);
+			vga_vesa_blanked = VESA_NO_BLANKING;
+		}
+		if (vga_palette_blanked) {
+			vga_set_palette(c, color_table);
+			vga_palette_blanked = false;
+			return 0;
+		}
+		vga_is_gfx = false;
+		/* Tell console.c that it has to restore the screen itself */
+		return 1;
+	case VESA_VSYNC_SUSPEND:	/* Normal blanking */
+		if (!mode_switch && vga_video_type == VIDEO_TYPE_VGAC) {
+			vga_pal_blank(&vgastate);
+			vga_palette_blanked = true;
+			return 0;
+		}
+		vgacon_set_origin(c);
+		scr_memsetw((void *) vga_vram_base, BLANK,
+			    c->vc_screenbuf_size);
+		if (mode_switch)
+			vga_is_gfx = true;
+		return 1;
+	default:		/* VESA blanking */
+		if (vga_video_type == VIDEO_TYPE_VGAC) {
+			vga_vesa_blank(&vgastate, blank - 1);
+			vga_vesa_blanked = blank;
+		}
+		return 0;
+	}
+}
+
+/*
+ * PIO_FONT support.
+ *
+ * The font loading code goes back to the codepage package by
+ * Joel Hoffman (joel@wam.umd.edu). (He reports that the original
+ * reference is: "From: p. 307 of _Programmer's Guide to PC & PS/2
+ * Video Systems_ by Richard Wilton. 1987.  Microsoft Press".)
+ *
+ * Change for certain monochrome monitors by Yury Shevchuck
+ * (sizif@botik.yaroslavl.su).
+ */
+
+#define colourmap 0xa0000
+/* Pauline Middelink <middelin@polyware.iaf.nl> reports that we
+   should use 0xA0000 for the bwmap as well.. */
+#define blackwmap 0xa0000
+#define cmapsz 8192
+
+static int vgacon_do_font_op(struct vgastate *state, char *arg, int set,
+		bool ch512)
+{
+	unsigned short video_port_status = vga_video_port_reg + 6;
+	int font_select = 0x00, beg, i;
+	char *charmap;
+	bool clear_attribs = false;
+	if (vga_video_type != VIDEO_TYPE_EGAM) {
+		charmap = (char *) VGA_MAP_MEM(colourmap, 0);
+		beg = 0x0e;
+	} else {
+		charmap = (char *) VGA_MAP_MEM(blackwmap, 0);
+		beg = 0x0a;
+	}
+
+	/*
+	 * All fonts are loaded in slot 0 (0:1 for 512 ch)
+	 */
+
+	if (!arg)
+		return -EINVAL;	/* Return to default font not supported */
+
+	font_select = ch512 ? 0x04 : 0x00;
+
+	raw_spin_lock_irq(&vga_lock);
+	/* First, the Sequencer */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+	/* CPU writes only to map 2 */
+	vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x04);	
+	/* Sequential addressing */
+	vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x07);	
+	/* Clear synchronous reset */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x03);
+
+	/* Now, the graphics controller, select map 2 */
+	vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x02);		
+	/* disable odd-even addressing */
+	vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x00);
+	/* map start at A000:0000 */
+	vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x00);
+	raw_spin_unlock_irq(&vga_lock);
+
+	if (arg) {
+		if (set)
+			for (i = 0; i < cmapsz; i++) {
+				vga_writeb(arg[i], charmap + i);
+				cond_resched();
+			}
+		else
+			for (i = 0; i < cmapsz; i++) {
+				arg[i] = vga_readb(charmap + i);
+				cond_resched();
+			}
+
+		/*
+		 * In 512-character mode, the character map is not contiguous if
+		 * we want to remain EGA compatible -- which we do
+		 */
+
+		if (ch512) {
+			charmap += 2 * cmapsz;
+			arg += cmapsz;
+			if (set)
+				for (i = 0; i < cmapsz; i++) {
+					vga_writeb(arg[i], charmap + i);
+					cond_resched();
+				}
+			else
+				for (i = 0; i < cmapsz; i++) {
+					arg[i] = vga_readb(charmap + i);
+					cond_resched();
+				}
+		}
+	}
+
+	raw_spin_lock_irq(&vga_lock);
+	/* First, the sequencer, Synchronous reset */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x01);	
+	/* CPU writes to maps 0 and 1 */
+	vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x03);
+	/* odd-even addressing */
+	vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x03);
+	/* Character Map Select */
+	if (set)
+		vga_wseq(state->vgabase, VGA_SEQ_CHARACTER_MAP, font_select);
+	/* clear synchronous reset */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x03);
+
+	/* Now, the graphics controller, select map 0 for CPU */
+	vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x00);
+	/* enable even-odd addressing */
+	vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x10);
+	/* map starts at b800:0 or b000:0 */
+	vga_wgfx(state->vgabase, VGA_GFX_MISC, beg);
+
+	/* if 512 char mode is already enabled don't re-enable it. */
+	if ((set) && (ch512 != vga_512_chars)) {
+		vga_512_chars = ch512;
+		/* 256-char: enable intensity bit
+		   512-char: disable intensity bit */
+		inb_p(video_port_status);	/* clear address flip-flop */
+		/* color plane enable register */
+		vga_wattr(state->vgabase, VGA_ATC_PLANE_ENABLE, ch512 ? 0x07 : 0x0f);
+		/* Wilton (1987) mentions the following; I don't know what
+		   it means, but it works, and it appears necessary */
+		inb_p(video_port_status);
+		vga_wattr(state->vgabase, VGA_AR_ENABLE_DISPLAY, 0);	
+		clear_attribs = true;
+	}
+	raw_spin_unlock_irq(&vga_lock);
+
+	if (clear_attribs) {
+		for (i = 0; i < MAX_NR_CONSOLES; i++) {
+			struct vc_data *c = vc_cons[i].d;
+			if (c && c->vc_sw == &vga_con) {
+				/* force hi font mask to 0, so we always clear
+				   the bit on either transition */
+				c->vc_hi_font_mask = 0x00;
+				clear_buffer_attributes(c);
+				c->vc_hi_font_mask = ch512 ? 0x0800 : 0;
+			}
+		}
+	}
+	return 0;
+}
+
+/*
+ * Adjust the screen to fit a font of a certain height
+ */
+static int vgacon_adjust_height(struct vc_data *vc, unsigned fontheight)
+{
+	unsigned char ovr, vde, fsr;
+	int rows, maxscan, i;
+
+	rows = vc->vc_scan_lines / fontheight;	/* Number of video rows we end up with */
+	maxscan = rows * fontheight - 1;	/* Scan lines to actually display-1 */
+
+	/* Reprogram the CRTC for the new font size
+	   Note: the attempt to read the overflow register will fail
+	   on an EGA, but using 0xff for the previous value appears to
+	   be OK for EGA text modes in the range 257-512 scan lines, so I
+	   guess we don't need to worry about it.
+
+	   The same applies for the spill bits in the font size and cursor
+	   registers; they are write-only on EGA, but it appears that they
+	   are all don't care bits on EGA, so I guess it doesn't matter. */
+
+	raw_spin_lock_irq(&vga_lock);
+	outb_p(0x07, vga_video_port_reg);	/* CRTC overflow register */
+	ovr = inb_p(vga_video_port_val);
+	outb_p(0x09, vga_video_port_reg);	/* Font size register */
+	fsr = inb_p(vga_video_port_val);
+	raw_spin_unlock_irq(&vga_lock);
+
+	vde = maxscan & 0xff;	/* Vertical display end reg */
+	ovr = (ovr & 0xbd) +	/* Overflow register */
+	    ((maxscan & 0x100) >> 7) + ((maxscan & 0x200) >> 3);
+	fsr = (fsr & 0xe0) + (fontheight - 1);	/*  Font size register */
+
+	raw_spin_lock_irq(&vga_lock);
+	outb_p(0x07, vga_video_port_reg);	/* CRTC overflow register */
+	outb_p(ovr, vga_video_port_val);
+	outb_p(0x09, vga_video_port_reg);	/* Font size */
+	outb_p(fsr, vga_video_port_val);
+	outb_p(0x12, vga_video_port_reg);	/* Vertical display limit */
+	outb_p(vde, vga_video_port_val);
+	raw_spin_unlock_irq(&vga_lock);
+	vga_video_font_height = fontheight;
+
+	for (i = 0; i < MAX_NR_CONSOLES; i++) {
+		struct vc_data *c = vc_cons[i].d;
+
+		if (c && c->vc_sw == &vga_con) {
+			if (con_is_visible(c)) {
+			        /* void size to cause regs to be rewritten */
+				cursor_size_lastfrom = 0;
+				cursor_size_lastto = 0;
+				c->vc_sw->con_cursor(c, true);
+			}
+			c->vc_font.height = c->vc_cell_height = fontheight;
+			vc_resize(c, 0, rows);	/* Adjust console size */
+		}
+	}
+	return 0;
+}
+
+static int vgacon_font_set(struct vc_data *c, const struct console_font *font,
+			   unsigned int vpitch, unsigned int flags)
+{
+	unsigned charcount = font->charcount;
+	int rc;
+
+	if (vga_video_type < VIDEO_TYPE_EGAM)
+		return -EINVAL;
+
+	if (font->width != VGA_FONTWIDTH || font->height > 32 || vpitch != 32 ||
+	    (charcount != 256 && charcount != 512))
+		return -EINVAL;
+
+	rc = vgacon_do_font_op(&vgastate, font->data, 1, charcount == 512);
+	if (rc)
+		return rc;
+
+	if (!(flags & KD_FONT_FLAG_DONT_RECALC))
+		rc = vgacon_adjust_height(c, font->height);
+	return rc;
+}
+
+static int vgacon_font_get(struct vc_data *c, struct console_font *font, unsigned int vpitch)
+{
+	if (vga_video_type < VIDEO_TYPE_EGAM || vpitch != 32)
+		return -EINVAL;
+
+	font->width = VGA_FONTWIDTH;
+	font->height = c->vc_font.height;
+	font->charcount = vga_512_chars ? 512 : 256;
+	if (!font->data)
+		return 0;
+	return vgacon_do_font_op(&vgastate, font->data, 0, vga_512_chars);
+}
+
+static int vgacon_resize(struct vc_data *c, unsigned int width,
+			 unsigned int height, bool from_user)
+{
+	if ((width << 1) * height > vga_vram_size)
+		return -EINVAL;
+
+	if (from_user) {
+		/*
+		 * Ho ho!  Someone (svgatextmode, eh?) may have reprogrammed
+		 * the video mode!  Set the new defaults then and go away.
+		 */
+		vga_si->orig_video_cols = width;
+		vga_si->orig_video_lines = height;
+		vga_default_font_height = c->vc_cell_height;
+		return 0;
+	}
+	if (width % 2 || width > vga_si->orig_video_cols ||
+	    height > (vga_si->orig_video_lines * vga_default_font_height)/
+	    c->vc_cell_height)
+		return -EINVAL;
+
+	if (con_is_visible(c) && !vga_is_gfx) /* who knows */
+		vgacon_doresize(c, width, height);
+	return 0;
+}
+
+static bool vgacon_set_origin(struct vc_data *c)
+{
+	if (vga_is_gfx ||	/* We don't play origin tricks in graphic modes */
+	    (console_blanked && !vga_palette_blanked))	/* Nor we write to blanked screens */
+		return false;
+	c->vc_origin = c->vc_visible_origin = vga_vram_base;
+	vga_set_mem_top(c);
+	vga_rolled_over = 0;
+	return true;
+}
+
+static void vgacon_save_screen(struct vc_data *c)
+{
+	static int vga_bootup_console = 0;
+
+	if (!vga_bootup_console) {
+		/* This is a gross hack, but here is the only place we can
+		 * set bootup console parameters without messing up generic
+		 * console initialization routines.
+		 */
+		vga_bootup_console = 1;
+		c->state.x = vga_si->orig_x;
+		c->state.y = vga_si->orig_y;
+	}
+
+	/* We can't copy in more than the size of the video buffer,
+	 * or we'll be copying in VGA BIOS */
+
+	if (!vga_is_gfx)
+		scr_memcpyw((u16 *) c->vc_screenbuf, (u16 *) c->vc_origin,
+			    c->vc_screenbuf_size > vga_vram_size ? vga_vram_size : c->vc_screenbuf_size);
+}
+
+static bool vgacon_scroll(struct vc_data *c, unsigned int t, unsigned int b,
+		enum con_scroll dir, unsigned int lines)
+{
+	unsigned long oldo;
+	unsigned int delta;
+
+	if (t || b != c->vc_rows || vga_is_gfx || c->vc_mode != KD_TEXT)
+		return false;
+
+	if (!vga_hardscroll_enabled || lines >= c->vc_rows / 2)
+		return false;
+
+	vgacon_restore_screen(c);
+	oldo = c->vc_origin;
+	delta = lines * c->vc_size_row;
+	if (dir == SM_UP) {
+		if (c->vc_scr_end + delta >= vga_vram_end) {
+			scr_memcpyw((u16 *) vga_vram_base,
+				    (u16 *) (oldo + delta),
+				    c->vc_screenbuf_size - delta);
+			c->vc_origin = vga_vram_base;
+			vga_rolled_over = oldo - vga_vram_base;
+		} else
+			c->vc_origin += delta;
+		scr_memsetw((u16 *) (c->vc_origin + c->vc_screenbuf_size -
+				     delta), c->vc_video_erase_char,
+			    delta);
+	} else {
+		if (oldo - delta < vga_vram_base) {
+			scr_memmovew((u16 *) (vga_vram_end -
+					      c->vc_screenbuf_size +
+					      delta), (u16 *) oldo,
+				     c->vc_screenbuf_size - delta);
+			c->vc_origin = vga_vram_end - c->vc_screenbuf_size;
+			vga_rolled_over = 0;
+		} else
+			c->vc_origin -= delta;
+		c->vc_scr_end = c->vc_origin + c->vc_screenbuf_size;
+		scr_memsetw((u16 *) (c->vc_origin), c->vc_video_erase_char,
+			    delta);
+	}
+	c->vc_scr_end = c->vc_origin + c->vc_screenbuf_size;
+	c->vc_visible_origin = c->vc_origin;
+	vga_set_mem_top(c);
+	c->vc_pos = (c->vc_pos - oldo) + c->vc_origin;
+	return true;
+}
+
+/*
+ *  The console `switch' structure for the VGA based console
+ */
+
+static void vgacon_clear(struct vc_data *vc, unsigned int sy, unsigned int sx,
+			 unsigned int width) { }
+static void vgacon_putcs(struct vc_data *vc, const u16 *s, unsigned int count,
+			 unsigned int ypos, unsigned int xpos) { }
+
+const struct consw vga_con = {
+	.owner = THIS_MODULE,
+	.con_startup = vgacon_startup,
+	.con_init = vgacon_init,
+	.con_deinit = vgacon_deinit,
+	.con_clear = vgacon_clear,
+	.con_putcs = vgacon_putcs,
+	.con_cursor = vgacon_cursor,
+	.con_scroll = vgacon_scroll,
+	.con_switch = vgacon_switch,
+	.con_blank = vgacon_blank,
+	.con_font_set = vgacon_font_set,
+	.con_font_get = vgacon_font_get,
+	.con_resize = vgacon_resize,
+	.con_set_palette = vgacon_set_palette,
+	.con_scrolldelta = vgacon_scrolldelta,
+	.con_set_origin = vgacon_set_origin,
+	.con_save_screen = vgacon_save_screen,
+	.con_build_attr = vgacon_build_attr,
+	.con_invert_region = vgacon_invert_region,
+};
+EXPORT_SYMBOL(vga_con);
+
+void vgacon_register_screen(struct screen_info *si)
+{
+	if (!si || vga_si)
+		return;
+
+	conswitchp = &vga_con;
+	vga_si = si;
+}
+
+MODULE_DESCRIPTION("VGA based console driver");
+MODULE_LICENSE("GPL");
-- 
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