"Input out of Range"

[Tom Horsley]

On Fri, 31 Oct 2014 11:49:38 -0700
Rick Stevens wrote:

> One way out is to plug the monitor into the box directly, boot up and
> verify that the screen comes up correctly. You can then get X to dump
> its settings and put those into an Xorg.conf file so it always uses
> those values. It won't matter then what the KVM spews out since X will
> use the information from the conf file.

That works up to the point where you try to modify the xorg.conf
file. X pays no attention to xorg.conf most of the time these
days. What does work is getting the EDID from the monitor and
stashing it in a firmware directory where you can use it to
force the kernel to override EDID any time anyone asks about it.

Get edid from currently connected monitor:

monitor-get-edid > /lib/firmware/edid.bin

Stick this on kernel options in grub config file:

drm_kms_helper.edid_firmware=edid.bin

Now the dadgum kernel will boot with the edid for the
monitor even if it isn't connected at boot time.