This kernel boot options tells the kernel KMS driver on what resolution and/or frequency to
use. For this to work, KMS must not be disabled (see above). The format of the option is as
follows:
Code:
video=conn:res[M][R][-bpp][@refresh][i][m][eDd]
This option can be specified multiple times, one for each different connection name - so you
can have on settings for VGA, one for HDMI, etc.
conn means the connection name, which depends how your monitor is connected to the system.
Listed are some common connection names, their names are self-explanatory:
VGA (VGA connector)
DVI-I (DVI connector, supporting both digital and analog - rare)
DVI-D (DVI connector, digital only)
DVI-A (DVI connector, analog only - rare)
composite (composite video)
s-video (S-video output)
LVDS (Laptop panel)
component (component video output)
displayport (Mac display)
HDMI-A (the first HDMI port)
HDMI-B (the second HDMI port)
TV (TV output)
res stands for the resolution. It is specified as widthxheight, in pixels (e.g. 800x600).
M if specified, means that the display timing frequency will be computed using VESA CVT
standard, otherwise a hard-coded timing table will be used.
R if specified, means that a "reduced blanking" display timing frequency will be used. This is
useful for digital displays (LVDS, DVI or HDMI). Otherwise standard timing will be used.
-bpp stands for bit-per-pixel, that is, the bit-depth of the display, that is, the number of
colours to be used. If not specified, the driver will choose the highest supported one. Common
values are:
-32 (32-bit per pixel: 16million colours)
-24 (24-bit per pixel: 16million colours)
-16 (16-bit per pixel: 64thousand colours) - you're unlike to use this nowadays
-15 (15-bit per pixel: 32thousand colours) - you're unlike to use this nowadays
-8 (8-bit per pixel: 256 colours) - you're unlike to use this nowadays
-4 (4-bit per pixel: 16 colours) - you're unlike to use this nowadays
@refresh specifies display refresh rate (also known as the vertical frequency refresh rate).
Usually @60 or @59 for digital displays, you can specify others for analog / CRT monitors. If
not specified the highest supported rate will be used.
i, if specified, means to use interlaced mode for calculation. Only makes sense for analog /
CRT monitors.
m, if specified, means add some margins to the display timing calculation (add 1.8% margin).
m, if specified, means add some margins to the display timing calculation (add 1.8% margin).
e, if specified, means to enable the port (even if no device/monitor is detected).
D, if specified, means to enable the port (even if no device/monitor is detected) and use the
Digital interface.
d, if specified, means to disable the port (even if there is a monitor attached there).
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