Resolution on SCFB X11 Driver

Polytropon freebsd at
Fri Jun 24 19:16:40 UTC 2016

On Fri, 24 Jun 2016 13:24:17 -0400, Charles W. Ross wrote:
> Hi all,
> I'm running FreeBSD 10.3 on an Intel NUC with 4th generation graphics.
> This is not supported by the i915 driver yet, so I'm using the SCFB
> (frame buffer) driver.
> It works, but I can't seem to set an optimal resolution. My display (24"
> Dell) supports 1920*1200, but the system only permits X11 to operate at
> 1280*1024.
> I have tried the usual settings in xorg.conf to define the display's
> "Modes" at 1920*1200, but no luck. Running 'xrandr' presents only one
> option: 1280*1024.
> I know the SCFB driver is capable of operating at higher resolutions,
> does anyone have any tips on how to set this?

Some years ago, I had a similar problem with the nvidia driver
not providing a screen size biiger than 1024x768 (which isn't
that great on an 21" 4:3 CRT), so I tested and collected some
tweaks for xorg.conf. Maybe those are driver-specific or even
outdated, but maybe they can be an inspiration for further

I did manually define the monitor's physical parameters to
allow X to calculate the required resolution and size:

Section "Monitor"
	Identifier	"Monitor0"
	VendorName	"Eizo"
	ModelName	"FlexScan F980"
	HorizSync	30.0 - 137.0
	VertRefresh	50.0 - 160.0
	Option		"DPMS"			"false"
	DisplaySize	410 305
	# X*Y in mm for DPI calculation, cf. xinit -- -dpi 72/75/96/115

In that section, if I set

	Option       "PreferredMode" "1920x1200"

the system locked up. No idea why.

Later on, I tried to set the DPI size and disable EDID information

Section "Device"
	Identifier	"Card0"
	Driver		"nvidia"
	Option		"UseEdid"		"FALSE"
	Option		"UseEdidDpi"		"FALSE"
	Option		"DPI"			"96 x 96"

In the "most important section" of xorg.conf, I could successfully
set the screen sizes to switch manually (with Ctrl+Alt+[+]/[-] keys)
or via program (for example games that activated a full screen mode
that was not the "usual" mode).

Section "Screen"
	Identifier	"Screen0"
	Device		"Card0"
	Monitor		"Monitor0"
	DefaultDepth	24
	SubSection "Display"
		Viewport	0 0
		Depth		24
		Visual		"TrueColor"
		Modes		"1400x1050" "1152x864" "1024x768" "800x600" "640x480" "320x240"

In case of a flat panel, all size settings should be the same, and
in the "Screen" section, there should be only one entry of the
desired format.

I always could manually switch to the desired mode:

	xrandr --fb 1400x1050
	xrandr --size 1400x1050

which I had temporarily put into ~/.xinitrc, but that looked wrong.

With "xrandr" without parameter) you should then get a list of the
available modes, with the one selected at the top.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

More information about the freebsd-questions mailing list