DragonFly On-Line Manual Pages

VGA(4)                DragonFly Kernel Interfaces Manual                VGA(4)

NAME
     vga - generic video card interface

SYNOPSIS
     device vga0 at isa? port ?

     options VGA_KEEP_POWERON_MODE
     options VGA_NO_FONT_LOADING
     options VGA_NO_MODE_CHANGE
     options VGA_DEBUG=N
     options VGA_WIDTH90

DESCRIPTION
     The vga driver is a generic video card driver which provides access to
     video cards.  This driver is required for the syscons(4) console driver
     which will call the vga driver to manipulate video hardware (changing
     video modes, loading fonts, etc).

     The vga driver supports the standard VGA video cards.

DRIVER CONFIGURATION
     The following kernel configuration options can be used to control the vga
     driver.  These options provide compatibility with certain VGA cards.

     VGA_DEBUG=N                Set the VGA support debug level to N.  The
                                default value is 0, which suppresses all
                                debugging output.  A value of 2 gives maximum
                                verbosity.

     VGA_KEEP_POWERON_MODE      This option keeps the initial mode's register
                                settings for switching back to it from another
                                mode.

     VGA_WIDTH90                This option enables 90 column modes: 90x25,
                                90x30, 90x43, 90x50, 90x60.  These modes are
                                not always supported by the video card and the
                                display.  It is highly likely that LCD display
                                cannot work with these modes.

     The following option will remove some features from the vga driver and
     save kernel memory.

     VGA_NO_FONT_LOADING        This option removes font loading from the
                                driver.  Note that if you use this option and
                                still wish to use the mouse on the console
                                then you must also use the SC_ALT_MOUSE_IMAGE
                                option.  See syscons(4).

     VGA_NO_MODE_CHANGE         This option prevents the driver from changing
                                video modes.

SEE ALSO
     vgl(3), syscons(4)

STANDARDS
     Apple, IBM, Motorola, "Common Hardware Reference Platform: I/O Device
     Reference", Appendix A: VGA Programming Model,
     ftp://ftp.software.ibm.com/rs6000/technology/spec/chrp/, p. 195.

HISTORY
     The vga driver first appeared in FreeBSD 3.1.

AUTHORS
     The vga driver was written by Soren Schmidt <sos@FreeBSD.org> and
     Kazutaka Yokota <yokota@FreeBSD.org>.  This manual page was written by
     Kazutaka Yokota.

DragonFly 5.9-DEVELOPMENT        March 3, 2020       DragonFly 5.9-DEVELOPMENT
VGA_SWITCHEROO(4)     DragonFly Kernel Interfaces Manual     VGA_SWITCHEROO(4)

NAME
     vga_switcheroo, apple_gmux -- support for Apple laptops with dual GPUs

SYNOPSIS
     To enable support of dual GPUs in kernel, include the following line in
     the kernel configuration file:

           options VGA_SWITCHEROO

     When the system has booted, load the apple_gmux driver before the native
     graphics drivers, for example i915(4).

     Alternatively, you can put these two lines in rc.conf(5):

           apple_gmux_load="YES"
           i915_load="YES"

     As a result, vga_switcheroo switches the gmux controller so that all
     output comes from the IGD.

DESCRIPTION
     Apple MacBook Pro laptops have hybrid graphics, i.e. two GPUs, one being
     the integrated graphics device (IGD) and the other being the discrete
     graphics device (DIS), sometimes called the dedicated graphics device.
     Gmux is a microcontroller that controls the output of these GPUs.

     vga_switcheroo is the higher level module that facilitates switching
     between the two GPUs using the lower level apple_gmux driver.  When the
     system boots and vga_switcheroo is enabled, apple_gmux registers with it.
     It then acts as a handler.  The two graphics adapters will also detect
     the presence of vga_switcheroo and register as clients.

IMPLEMENTATION NOTES
     In the current DragonFly specific implementation, upon detecting the
     presence of apple_gmux, the Intel driver will call vga_switcheroo to
     switch the gmux so that all output comes from the IGD.  Switching to DIS
     is not yet supported.

HARDWARE
     Apple MacBook Pro laptops with dual GPUs.

SEE ALSO
     i915(4), rc.conf(5)

     https://01.org/linuxgraphics/gfx-docs/drm/gpu/vga-switcheroo.html

HISTORY
     The vga_switcheroo driver was added in DragonFly 4.9.

AUTHORS
     The vga_switcheroo driver was ported to DragonFly from linux 4.8 by
     Peeter Must.  He also wrote this manual page.

DragonFly 4.7                    May 30, 2017                    DragonFly 4.7