MFC r332421: vt: add three more cp437 mappings for vga textmode

In UTF-8 locales mandoc uses a number of characters outside of the Basic
Latin group, e.g. from general punctuation or miscellaneous mathematical
symbols, and these rendered as ? in text mode.

This change adds (char, replacement, code point, description):

– - U+2013 En Dash
⟨ < U+27E8 Mathematical Left Angle Bracket
⟩ > U+27E9 Mathematical Right Angle Bracket

This change addresses some common cases; there are others that still
need to be added after a more thorough review.

PR: 227409
Sponsored by: The FreeBSD Foundation

MFC r319928:

Use nitems(..) when computing `max` instead of the longhand version of
the same logic

MFC 297334

vt: Use textmode when we're running on hypervisors

The graphic mode is noticeably slow on hypervisors, especially
on Hyper-V (1 second to each line).

Submitted by: Dexuan Cui <decui microsoft com>
Reviewed by: kib, sephe, royger (early loader version)
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5739

MFC r286667 & r286723

Better support memory mapped console devices, such as VGA and EFI
frame buffers and memory mapped UARTs.

PR: 191564, 194952, 202276

vt(4): Merge several bug fixes and improvements

SVN revisions in this MFC:
269779 270705 270706 271180 271250 271253 271682 271684

Detailed commit list:

r269779:
fbd: Fix a bug where vt_fb_attach() success would be considered a failure

vt_fb_attach() currently always returns 0, but it could return a code
defined in errno.h. However, it doesn't return a CN_* code. So checking
its return value against CN_DEAD (which is 0) is incorrect, and in this
case, a success becomes a failure.

The consequence was unimportant, because the caller (drm_fb_helper.c)
would only log an error message in this case. The console would still
work.

Approved by: nwhitehorn

r270705:
vt(4): Add cngrab() and cnungrab() callbacks

They are used when a panic occurs or when entering a DDB session for
instance.

cngrab() forces a vt-switch to the console window, no matter if the
original window is another terminal or an X session. However, cnungrab()
doesn't vt-switch back to the original window currently.

r270706:
drm: Don't "taskqueue" vt-switch if under DDB/panic situation

If DDB is active, we can't use a taskqueue thread to switch away from
the X window, because this thread can't run.

Reviewed by: ray@
Approved by: ray@

r271180:
vt_vga: vd_setpixel_t and vd_drawrect_t are noop in text mode

r271250:
vt(4): Change the terminal and buffer sizes, even without a font

This fixes a bug where scroll lock would not work for tty #0 when using
vt_vga's textmode. The reason was that this window is created with a
static 256x100 buffer, larger than the real size of 80x25.

Now, in vt_change_font() and vt_compute_drawable_area(), we still
perform operations even of the window has no font loaded (this is the
case in textmode here vw->vw_font == NULL). One of these operation
resizes the buffer accordingly.

In vt_compute_drawable_area(), we take the terminal size as is (ie.
80x25) for the drawable area.

The font argument to vt_set_border() is removed (it was never used) and
the code now uses the computed drawable area instead of re-doing its own
calculation.

Reported by: Harald Schmalzbauer <h.schmalzbauer_omnilan.de>
Tested by: Harald Schmalzbauer <h.schmalzbauer_omnilan.de>

r271253:
pause_sbt(): Take the cold path (ie. use DELAY()) if KDB is active

This fixes a panic in the i915 driver when one uses debug.kdb.enter=1
under vt(4).

PR: 193269
Reported by: emaste@
Submitted by: avg@

r271682:
vt(4): Fix a LOR which occurs during a call to vt_upgrade()

Reported by: kib@
Review: https://reviews.freebsd.org/D785
Reviewed by: ray@
Approved by: ray@

r271684:
vt(4): Use vt_fb_drawrect() and vt_fb_setpixel() in all vt_fb-derivative

Review: https://reviews.freebsd.org/D789
Reviewed by: nwhitehorn
Approved by: nwhitehorn

Approved by: re (gjb)

MFC vt(4) improvements / sync with HEAD

These are largely dumbbell@'s changes. Most significantly they address
the extreme performance degradation with VGA hardware.

SVN revisions in this MFC:
269471 270290 270293 270322 270324 270329 270331 270336 270338 270340
270341 270342 270343 270388 270390 270404 270411 270412 270413 270431
270446 270448 270485 270587 270589 270613 270618 270620 270667 270702
270707 270708 270720 270721 270785 270786

Detailed commit list:

r270290: Test if the cursor is shown only once

Later, we just see if the "struct mouse_cursor" pointer is set. This
avoids the need to mess with all the conditions several times; this
has been error prone.

While here, rename the variable "m" to a more meaningful "cursor",
like it's done elsewhere in the code.

r270293: Rename the "mouse_cursor" structure to "vt_mouse_cursor"

At the same time, "w" and "h" members are now called "width" and
"height". The goal is to have a more "public" structure, because it
will soon be passed as argument to a new callback, replacing
vd_bitbltchr_t.

r269471 (ray):

Fix vt_vga driver to draw not-8-bit-aligned fonts correctly.
Still one bug here: mouse left some gaps on track when moving left.

r270322:

Add new vd_bitblt_text_t callback, and implement it for vt_vga

Compared to the deprecated vd_bitbltchr_t callback, vd_bitblt_text_t
receives:
o the whole text buffer
o the dirty area
o the mouse cursor (map, position, colors)

This allows the backend to perform optimization on how to draw things.
The goal is to remove vd_bitbltchr_t and vd_putchar_t, once all driver
are converted (only vt_vga is included in this commit).

In vt_vga, this allows to draw the text and the cursor in one pass,
without ever reading from video memory (because it has all the context).
The main benefit is the speed improvement: no more slideshow during
boot!

Other bugs fixed in vt_vga are:
o left-most characters are drawn properly (the left-most pixels were
missing with bold characters and some wide letters such as 'm')
o no more black square around the cursor
o no cursor flickering when the text is scrolling

There are still many problems to fix: the known issues are marked with
"FIXME" inside the code.

r270411:

vt_fb: Implement vd_bitblt_text_t for vt_fb and derivatives

r270412:

creator_fb: Implement vd_bitblt_text_t

r270413: ofwfb: Implement vd_bitblt_text_t

r270324: vt_vga: Clip the draw area to never draw offscreen

This fixes a bug when two windows use different fonts, but a longer-
term solution is required. The dirty area should be stored as pixels,
not character cells, because such coordinates don't have the same
meaning in all windows, when using different fonts.

r270329: Mark new mouse position as dirty only when it's actually displayed

r270331: Store cursor bitmap & colors in struct vt_device

This removes the need to specify them to each call to vd_bitblt_text_t
and, therefore, simplifies the API.

r270336: Give the window to vd_bitblt_text_t callback

... instead of both the buffer and the font. Again, this simplifies
the API.

r270338: The offset to center the text area is per-window now

The previous global offset, based on the last loaded font, had no
meaning for other windows. This caused a shifted text area, often
partly out-of-screen.

r270341: vt_vga: Remove a "FIXME" comment; the issue was solved in r270338

r270340: Don't run vt_set_border() and vt_flush() concurrently

In the case of vt_vga, the two concurrent calls were writing to the
same VGA registers, causing incorrect refresh of the screen.

r270342: Use the actual size of the mouse when marking its position as dirty

This fixes a bug where part of the cursor was not erased.

r270343: Remove "FIXME" about multiple locking of vt_buf in vt_flush()

After some testing, it appears that acquiring the lock once and keeping
it longer is slower than taking it multiple times.

While here, fix a typo in another comment.

r270388: vt_vga: Give only the character part of term_char_t to vga_get_cp437()

This fixes a bug where vga_get_cp437() was called with an invalid
argument. The screen was then filled with '?' instead of the actual
character.

r270390: Fix a crash in vt_mark_mouse_position_as_dirty() when in textmode

In textmode, no font is loaded, thus the page fault in
vt_mark_mouse_position_as_dirty() when it wants the font width/height.

For now, create a fake area for the textmode. This needs to be
modified if vt_vga gains mouse support in textmode.

While here, fix a build failure when SC_NO_CUTPASTE is defined:
vt_mark_mouse_position_as_dirty() must not be included in this case.

r270404: Fix cursor handling in vt_flush()

There were situations where the cursor was not erased/redrawn or its
position was marked as dirty even though it's not displayed. The code
is now more straightforward.

At the same, add a function to determine if the cursor covers a given
area. This is used by backends to know if they need to draw the
cursor.

This new function should be paired with a new state in struct
vt_device, called vd_mshown, which indicates if the cursor should be
displayed. This again simplifies vd_bitblt_text_t callback's API.

r270431: vt(4): Add vd_bitblt_bmp_t callback

The code was already there in all backends, we just expose it. This is
used to display the splash screen.

r270446: Remove vd_bitbltchr_t

It's replaced by vd_bitblt_text_t, which gives more context to the
backend and allows it to perform more efficiently when redrawing a
given area.

r270448: Fix order of arguments (x <-> y) when showing the splash screen

r270485: vt_vga: Fix the display of the splash screen

r270587: Take font offset into account in vt_is_cursor_in_area()

This fixes a "General protection fault" in vt_vga, where
vt_is_cursor_in_area() erroneously reported that the cursor was over
the text. This led to negative integers stored in "unsigned int" and
chaos.

r270589: The cursor coordinates are relative to the drawn area

... not the whole screen. Don't use font offsets in
vt_mark_mouse_position_as_dirty().

This fixes a bug where the mouse position wasn't marked as dirty when
approaching the borders of the drawn area.

r270613: Store a rectangle for the drawable area, not just the top-left corner

This allows backends to verify they do not draw outside of this area.
This fixes a bug in vt_vga where the text was happily drawn over the
right and bottom margins, when using the Gallant font.

r270618: Intialize drawable area rectangle each time a font is loaded

This also fixes a problem where early in boot, the area was zero,
leading to nothing displayed for a few seconds.

r270620: vt_vga: Use Write Mode 0 to draw group of 8 pixels using 3 or more colors

This replaces the method based on Write Mode 3, which required reads
from the video memory to load the latches.

r270667: When creating a window buffer, fill it entirely

... not just the visible part.

This fixes a bug where, when switching from eg. vt_vga to vt_fb (ie.
the resolution goes up), the originally hidden, uninitialized area of
the buffer is displayed on the screen. This leads to a missing text
cursor when it's over an unitialized area.

This was also visible when selecting text: the uninitialized area was
not highlighted.

Internally, this area was zeroed: characters were all 0x00000000,
meaning the foreground and background color was black. Now, everything
is filled with a space with a gray foreground color, like the visible
area.

While here, remove the check for the mute flag and always use
TERMINAL_NORM_ATTR as the character attribute (ie. gray foreground,
black background).

r270702: Implement basic support for KDSETMODE ioctl

With the current implementation, this allows an X11 server to tell
the console it switches a particular window in "graphics mode". This
information is used by the mouse handling code to ignore sysmouse events
in the window taken by the X server: only him should receive those
events.

r270707: Pause the vt_flush() timer when the screen is up-to-date

The timer is restarted whenever a window buffer is marked as dirty or
the mouse cursor moves.

There's still room for improvement. For instance, we should not mark a
window buffer as dirty when this window isn't displayed.

r270708: vt(4): Recompute the drawable area when the resolution changes

This was only done when the font changed.

r270720: vt(4): Fix mouse cursor handling in vt_fb/creator_vt/ofwfb

There were two issues:
1. The area given to vt_is_cursor_in_area() was adding the drawable
area offset, something already handled by this function.
2. The cursor was shifted on the screen by the offset of this area
and thus was misplaced or not erased. Furthermore, when reaching
the bottom or right borders, the cursor was either totally
removed or not erased correctly.

r270721: vt(4): If the terminal shrinks, make sure the mouse is inside
the new area

r270785: vt(4): Change vb_history_size from "int" to "unsigned int"

CID: 1230002, 1230003

r270786: Indicate that KDSETRAD case falls through the next case

CID: 1229953

Relnotes: Yes

MFC r270299 (dumbbell): vt_vga: When clearing video memory, don't read from it

The goal is to clear the video memory, in case an application drew to
it. So the content shouldn't be loaded in the latches, it can't be
trusted anyway.

This improves a bit the window switch speed.

Sponsored by: The FreeBSD Foundation

MFC r269685 (nwhitehorn): Retire vd_maskbitbltchr.

The same functionality can be obtained by testing for mask != NULL in
vd_bitbltchr, which all implementations of vd_bitbltchr() were doing
anyway.

Sponsored by: The FreeBSD Foundation

267622 Log:
Rename vt(4) vga module to dismiss interference with syscons(4) vga module.
267623 Log:
Remove stale link to deleted vt(4) xboxfb driver.
267624 Log:
syscons(4) and vt(4) can be built together now.
267625 Log:
Allow to disable syscons(4) if "hw.syscons.disable" kenv is set.
267626 Log:
Suspend vt(4) initialization if "kern.vt.disable" kenv is set.
267965 by emaste@ Log:
Use a common tunable to choose between vt(4)/sc(4)
With this change and previous work from ray@ it will be possible to put
both in GENERIC, and have one enabled by default, but allow the other to
be selected via the loader.
(The previous implementation had separate kern.vt.disable and
hw.syscons.disable tunables, and would panic if both drivers were
compiled in and neither was explicitly disabled.)
268175 by emaste@ Log:
Fix vt(4) detection in kbdcontrol and vidcontrol
As sc(4) and vt(4) coexist and are both enabled in GENERIC, the existence
of a vt(4) sysctl is not sufficient to determine that vt(4) is in use.
Reported by: Trond Endrestøl
268045 by emaste@ Log:
Add vt(4) to GENERIC and retire the separate VT config
vt(4) and sc(4) can now coexist in the same kernel. To choose the vt
driver, set the loader tunable kern.vty=vt .

Sponsored by: The FreeBSD Foundation

MFC r286667 & r286723

Better support memory mapped console devices, such as VGA and EFI
frame buffers and memory mapped UARTs.

PR: 191564, 194952, 202276

vt(4): Merge several bug fixes and improvements

SVN revisions in this MFC:
269779 270705 270706 271180 271250 271253 271682 271684

Detailed commit list:

r269779:
fbd: Fix a bug where vt_fb_attach() success would be considered a failure

vt_fb_attach() currently always returns 0, but it could return a code
defined in errno.h. However, it doesn't return a CN_* code. So checking
its return value against CN_DEAD (which is 0) is incorrect, and in this
case, a success becomes a failure.

The consequence was unimportant, because the caller (drm_fb_helper.c)
would only log an error message in this case. The console would still
work.

Approved by: nwhitehorn

r270705:
vt(4): Add cngrab() and cnungrab() callbacks

They are used when a panic occurs or when entering a DDB session for
instance.

cngrab() forces a vt-switch to the console window, no matter if the
original window is another terminal or an X session. However, cnungrab()
doesn't vt-switch back to the original window currently.

r270706:
drm: Don't "taskqueue" vt-switch if under DDB/panic situation

If DDB is active, we can't use a taskqueue thread to switch away from
the X window, because this thread can't run.

Reviewed by: ray@
Approved by: ray@

r271180:
vt_vga: vd_setpixel_t and vd_drawrect_t are noop in text mode

r271250:
vt(4): Change the terminal and buffer sizes, even without a font

This fixes a bug where scroll lock would not work for tty #0 when using
vt_vga's textmode. The reason was that this window is created with a
static 256x100 buffer, larger than the real size of 80x25.

Now, in vt_change_font() and vt_compute_drawable_area(), we still
perform operations even of the window has no font loaded (this is the
case in textmode here vw->vw_font == NULL). One of these operation
resizes the buffer accordingly.

In vt_compute_drawable_area(), we take the terminal size as is (ie.
80x25) for the drawable area.

The font argument to vt_set_border() is removed (it was never used) and
the code now uses the computed drawable area instead of re-doing its own
calculation.

Reported by: Harald Schmalzbauer <h.schmalzbauer_omnilan.de>
Tested by: Harald Schmalzbauer <h.schmalzbauer_omnilan.de>

r271253:
pause_sbt(): Take the cold path (ie. use DELAY()) if KDB is active

This fixes a panic in the i915 driver when one uses debug.kdb.enter=1
under vt(4).

PR: 193269
Reported by: emaste@
Submitted by: avg@

r271682:
vt(4): Fix a LOR which occurs during a call to vt_upgrade()

Reported by: kib@
Review: https://reviews.freebsd.org/D785
Reviewed by: ray@
Approved by: ray@

r271684:
vt(4): Use vt_fb_drawrect() and vt_fb_setpixel() in all vt_fb-derivative

Review: https://reviews.freebsd.org/D789
Reviewed by: nwhitehorn
Approved by: nwhitehorn

Approved by: re (gjb)

MFC vt(4) improvements / sync with HEAD

These are largely dumbbell@'s changes. Most significantly they address
the extreme performance degradation with VGA hardware.

SVN revisions in this MFC:
269471 270290 270293 270322 270324 270329 270331 270336 270338 270340
270341 270342 270343 270388 270390 270404 270411 270412 270413 270431
270446 270448 270485 270587 270589 270613 270618 270620 270667 270702
270707 270708 270720 270721 270785 270786

Detailed commit list:

r270290: Test if the cursor is shown only once

Later, we just see if the "struct mouse_cursor" pointer is set. This
avoids the need to mess with all the conditions several times; this
has been error prone.

While here, rename the variable "m" to a more meaningful "cursor",
like it's done elsewhere in the code.

r270293: Rename the "mouse_cursor" structure to "vt_mouse_cursor"

At the same time, "w" and "h" members are now called "width" and
"height". The goal is to have a more "public" structure, because it
will soon be passed as argument to a new callback, replacing
vd_bitbltchr_t.

r269471 (ray):

Fix vt_vga driver to draw not-8-bit-aligned fonts correctly.
Still one bug here: mouse left some gaps on track when moving left.

r270322:

Add new vd_bitblt_text_t callback, and implement it for vt_vga

Compared to the deprecated vd_bitbltchr_t callback, vd_bitblt_text_t
receives:
o the whole text buffer
o the dirty area
o the mouse cursor (map, position, colors)

This allows the backend to perform optimization on how to draw things.
The goal is to remove vd_bitbltchr_t and vd_putchar_t, once all driver
are converted (only vt_vga is included in this commit).

In vt_vga, this allows to draw the text and the cursor in one pass,
without ever reading from video memory (because it has all the context).
The main benefit is the speed improvement: no more slideshow during
boot!

Other bugs fixed in vt_vga are:
o left-most characters are drawn properly (the left-most pixels were
missing with bold characters and some wide letters such as 'm')
o no more black square around the cursor
o no cursor flickering when the text is scrolling

There are still many problems to fix: the known issues are marked with
"FIXME" inside the code.

r270411:

vt_fb: Implement vd_bitblt_text_t for vt_fb and derivatives

r270412:

creator_fb: Implement vd_bitblt_text_t

r270413: ofwfb: Implement vd_bitblt_text_t

r270324: vt_vga: Clip the draw area to never draw offscreen

This fixes a bug when two windows use different fonts, but a longer-
term solution is required. The dirty area should be stored as pixels,
not character cells, because such coordinates don't have the same
meaning in all windows, when using different fonts.

r270329: Mark new mouse position as dirty only when it's actually displayed

r270331: Store cursor bitmap & colors in struct vt_device

This removes the need to specify them to each call to vd_bitblt_text_t
and, therefore, simplifies the API.

r270336: Give the window to vd_bitblt_text_t callback

... instead of both the buffer and the font. Again, this simplifies
the API.

r270338: The offset to center the text area is per-window now

The previous global offset, based on the last loaded font, had no
meaning for other windows. This caused a shifted text area, often
partly out-of-screen.

r270341: vt_vga: Remove a "FIXME" comment; the issue was solved in r270338

r270340: Don't run vt_set_border() and vt_flush() concurrently

In the case of vt_vga, the two concurrent calls were writing to the
same VGA registers, causing incorrect refresh of the screen.

r270342: Use the actual size of the mouse when marking its position as dirty

This fixes a bug where part of the cursor was not erased.

r270343: Remove "FIXME" about multiple locking of vt_buf in vt_flush()

After some testing, it appears that acquiring the lock once and keeping
it longer is slower than taking it multiple times.

While here, fix a typo in another comment.

r270388: vt_vga: Give only the character part of term_char_t to vga_get_cp437()

This fixes a bug where vga_get_cp437() was called with an invalid
argument. The screen was then filled with '?' instead of the actual
character.

r270390: Fix a crash in vt_mark_mouse_position_as_dirty() when in textmode

In textmode, no font is loaded, thus the page fault in
vt_mark_mouse_position_as_dirty() when it wants the font width/height.

For now, create a fake area for the textmode. This needs to be
modified if vt_vga gains mouse support in textmode.

While here, fix a build failure when SC_NO_CUTPASTE is defined:
vt_mark_mouse_position_as_dirty() must not be included in this case.

r270404: Fix cursor handling in vt_flush()

There were situations where the cursor was not erased/redrawn or its
position was marked as dirty even though it's not displayed. The code
is now more straightforward.

At the same, add a function to determine if the cursor covers a given
area. This is used by backends to know if they need to draw the
cursor.

This new function should be paired with a new state in struct
vt_device, called vd_mshown, which indicates if the cursor should be
displayed. This again simplifies vd_bitblt_text_t callback's API.

r270431: vt(4): Add vd_bitblt_bmp_t callback

The code was already there in all backends, we just expose it. This is
used to display the splash screen.

r270446: Remove vd_bitbltchr_t

It's replaced by vd_bitblt_text_t, which gives more context to the
backend and allows it to perform more efficiently when redrawing a
given area.

r270448: Fix order of arguments (x <-> y) when showing the splash screen

r270485: vt_vga: Fix the display of the splash screen

r270587: Take font offset into account in vt_is_cursor_in_area()

This fixes a "General protection fault" in vt_vga, where
vt_is_cursor_in_area() erroneously reported that the cursor was over
the text. This led to negative integers stored in "unsigned int" and
chaos.

r270589: The cursor coordinates are relative to the drawn area

... not the whole screen. Don't use font offsets in
vt_mark_mouse_position_as_dirty().

This fixes a bug where the mouse position wasn't marked as dirty when
approaching the borders of the drawn area.

r270613: Store a rectangle for the drawable area, not just the top-left corner

This allows backends to verify they do not draw outside of this area.
This fixes a bug in vt_vga where the text was happily drawn over the
right and bottom margins, when using the Gallant font.

r270618: Intialize drawable area rectangle each time a font is loaded

This also fixes a problem where early in boot, the area was zero,
leading to nothing displayed for a few seconds.

r270620: vt_vga: Use Write Mode 0 to draw group of 8 pixels using 3 or more colors

This replaces the method based on Write Mode 3, which required reads
from the video memory to load the latches.

r270667: When creating a window buffer, fill it entirely

... not just the visible part.

This fixes a bug where, when switching from eg. vt_vga to vt_fb (ie.
the resolution goes up), the originally hidden, uninitialized area of
the buffer is displayed on the screen. This leads to a missing text
cursor when it's over an unitialized area.

This was also visible when selecting text: the uninitialized area was
not highlighted.

Internally, this area was zeroed: characters were all 0x00000000,
meaning the foreground and background color was black. Now, everything
is filled with a space with a gray foreground color, like the visible
area.

While here, remove the check for the mute flag and always use
TERMINAL_NORM_ATTR as the character attribute (ie. gray foreground,
black background).

r270702: Implement basic support for KDSETMODE ioctl

With the current implementation, this allows an X11 server to tell
the console it switches a particular window in "graphics mode". This
information is used by the mouse handling code to ignore sysmouse events
in the window taken by the X server: only him should receive those
events.

r270707: Pause the vt_flush() timer when the screen is up-to-date

The timer is restarted whenever a window buffer is marked as dirty or
the mouse cursor moves.

There's still room for improvement. For instance, we should not mark a
window buffer as dirty when this window isn't displayed.

r270708: vt(4): Recompute the drawable area when the resolution changes

This was only done when the font changed.

r270720: vt(4): Fix mouse cursor handling in vt_fb/creator_vt/ofwfb

There were two issues:
1. The area given to vt_is_cursor_in_area() was adding the drawable
area offset, something already handled by this function.
2. The cursor was shifted on the screen by the offset of this area
and thus was misplaced or not erased. Furthermore, when reaching
the bottom or right borders, the cursor was either totally
removed or not erased correctly.

r270721: vt(4): If the terminal shrinks, make sure the mouse is inside
the new area

r270785: vt(4): Change vb_history_size from "int" to "unsigned int"

CID: 1230002, 1230003

r270786: Indicate that KDSETRAD case falls through the next case

CID: 1229953

Relnotes: Yes

MFC r270299 (dumbbell): vt_vga: When clearing video memory, don't read from it

The goal is to clear the video memory, in case an application drew to
it. So the content shouldn't be loaded in the latches, it can't be
trusted anyway.

This improves a bit the window switch speed.

Sponsored by: The FreeBSD Foundation

MFC r269685 (nwhitehorn): Retire vd_maskbitbltchr.

The same functionality can be obtained by testing for mask != NULL in
vd_bitbltchr, which all implementations of vd_bitbltchr() were doing
anyway.

Sponsored by: The FreeBSD Foundation

267622 Log:
Rename vt(4) vga module to dismiss interference with syscons(4) vga module.
267623 Log:
Remove stale link to deleted vt(4) xboxfb driver.
267624 Log:
syscons(4) and vt(4) can be built together now.
267625 Log:
Allow to disable syscons(4) if "hw.syscons.disable" kenv is set.
267626 Log:
Suspend vt(4) initialization if "kern.vt.disable" kenv is set.
267965 by emaste@ Log:
Use a common tunable to choose between vt(4)/sc(4)
With this change and previous work from ray@ it will be possible to put
both in GENERIC, and have one enabled by default, but allow the other to
be selected via the loader.
(The previous implementation had separate kern.vt.disable and
hw.syscons.disable tunables, and would panic if both drivers were
compiled in and neither was explicitly disabled.)
268175 by emaste@ Log:
Fix vt(4) detection in kbdcontrol and vidcontrol
As sc(4) and vt(4) coexist and are both enabled in GENERIC, the existence
of a vt(4) sysctl is not sufficient to determine that vt(4) is in use.
Reported by: Trond Endrestøl
268045 by emaste@ Log:
Add vt(4) to GENERIC and retire the separate VT config
vt(4) and sc(4) can now coexist in the same kernel. To choose the vt
driver, set the loader tunable kern.vty=vt .

Sponsored by: The FreeBSD Foundation