VGA(4) OpenBSD Programmer's Manual VGA(4)
NAME
vga - VGA graphics driver for wscons
SYNOPSIS
vga0 at isa?
vga* at pci?
wsdisplay* at vga?
option PCIAGP
DESCRIPTION
This driver handles VGA graphics hardware within the wscons(4) console
framework. It doesn't provide direct device driver entry points but
makes its functions available via the internal wsdisplay(4) interface.
The vga driver supports multiple virtual screens on one physical display.
The screens allocated on one display can be of different ``types'', where
a type refers to various display properties. The type is determined at
the time the virtual screen is created and can't be changed later.
Screens are either created at kernel startup (then the default type is
used) or later with help of the wsconscfg(8) utility.
Currently, the following screen types are supported:
80x25 This is the standard VGA text mode with 80 columns and 25 rows.
16 different colors can be displayed at the same time. Charac-
ters are 8 x 16 pixels large, and a font consists of 256 charac-
ters. A built-in font of this size is always present on a VGA
card. It's also possible to use a downloaded font instead.
80x25bf A modified version of the previous. It only allows 8 colors to
be displayed. In exchange, it can access two fonts at the same
time, so that 512 different characters can be displayed.
80x40 A text mode with 80 columns and 40 rows. Similar to the standard
mode, 16 colors and 256 characters are available. Characters are
8 x 10 pixels large. For this mode to be useful, a font of that
character size must be downloaded.
80x40bf A modified version of the previous. It only allows 8 colors to
be displayed. In exchange, it can access two fonts at the same
time, so that 512 different characters can be displayed.
80x50 A text mode with 80 columns and 50 rows. Similar to the standard
mode, 16 colors and 256 characters are available. Characters are
8 x 8 pixels large. For this mode to be useful, a font of that
character size must be downloaded.
80x50bf A modified version of the previous. It only allows 8 colors to
be displayed. In exchange, it can access two fonts at the same
time, so that 512 different characters can be displayed.
80x24 A variant of the ``80x25'' screen type which displays 24 lines
only. It uses the standard 8x16 VGA font. This mode might be
useful for applications which depend on closer DEC VT100 compati-
bility.
80x24bf A modified version of the previous. It only allows 8 colors to
be displayed. In exchange, it can access two fonts at the same
time, so that 512 different characters can be displayed.
The vga driver can display fonts of the original IBM type and ISO-8859-1
encoded fonts. As an experimental feature, the ``higher half'' fonts of
the former OpenBSD/i386 pcvt driver distribution can be used too if
option WSCONS_SUPPORT_PCVTFONTS was set at kernel compile time. This is
only useful with the ``*bf'' screen types; a font containing the ASCII
range of characters must be available too on this screen.
AGP SUPPORT
option PCIAGP enables support for programming the AGP GART through
ioctl(2), which is used by the X server on some architectures.
The following ioctl(2) operations can be performed on /dev/ttyC0, and are
defined in <sys/agpio.h>:
AGPIOC_INFO
Returns information about the AGP subsystem. The result is a
pointer to the following structure:
typedef struct _agp_info {
agp_version version; /* version of driver (unused) */
u_int32_t bridge_id; /* bridge vendor/device */
u_int32_t agp_mode; /* mode info of bridge */
off_t aper_base; /* base of aperture */
size_t aper_size; /* size of aperture */
size_t pg_total; /* max pages (swap + system) */
size_t pg_system; /* max pages (system) */
size_t pg_used; /* current pages used */
} agp_info;
AGPIOC_ACQUIRE
Acquire control of the AGP chipset for use by this client. Re-
turns EBUSY if the AGP chipset is already acquired by another
client.
AGPIOC_RELEASE
Release control of the AGP chipset. This does not unbind or free
any allocated memory, which is the responsibility of the client
to handle if necessary.
AGPIOC_SETUP
Enable the AGP hardware with the relevant mode. This ioctl(2)
takes the following structure:
typedef struct _agp_setup {
u_int32_t agp_mode; /* mode info of bridge */
} agp_setup;
The mode bits are defined in <sys/agpio.h>.
AGPIOC_ALLOCATE
Allocate physical memory suitable for mapping into the AGP aper-
ture. This ioctl(2) takes the following structure:
typedef struct _agp_allocate {
int key; /* tag of allocation */
size_t pg_count; /* number of pages */
u_int32_t type; /* 0 == normal, other devspec */
u_int32_t physical; /* device specific (some devices
* need a phys address of the
* actual page behind the gatt
* table) */
} agp_allocate;
It returns a handle to the allocated memory.
AGPIOC_DEALLOCATE
Free the previously allocated memory associated with the handle
passed.
AGPIOC_BIND
Bind the allocated memory at given offset with the AGP aperture.
Returns EINVAL if the memory is already bound or the offset is
not at AGP page boundary. This ioctl(2) takes the following
structure:
typedef struct _agp_bind {
int key; /* tag of allocation */
off_t pg_start; /* starting page to populate */
} agp_bind;
The tag of allocation is the handle returned by AGPIOC_ALLOCATE.
AGPIOC_UNBIND
Unbind memory from the AGP aperture. Returns EINVAL if the memo-
ry is not bound. This ioctl(2) takes the following structure:
typedef struct _agp_unbind {
int key; /* tag of allocation */
u_int32_t priority; /* priority for paging out */
} agp_unbind;
SEE ALSO
ioctl(2), intro(4), isa(4), pcdisplay(4), pci(4), wscons(4),
wsdisplay(4), wsconscfg(8), wsfontload(8)
BUGS
Only a subset of the possible text modes is supported.
VGA cards are supposed to emulate an MDA if a monochrome display is con-
nected. In this case, the device will naturally not support colors at
all, but offer the capability to display underlined characters instead.
The ``80x25bf'', ``80x40bf'', ``80x50bf'', and ``80x24bf'' screen types
will not be available. This mode of operation is not tested.
OpenBSD 4.0 March 20, 1999 3