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#1 2016-11-30 08:37:59

sweisman
Member
Registered: 2008-05-20
Posts: 42

KMS Kernel Mode Setting problem on notebook boot.

I have a Sony Vaio T13 Ultrabook (3rd generation i7). It has VGA and HDMI ports, and can drive both simultaneously.

When I installed Arch 3/2015, the notebook booted appropriately. If both the ports had cables, the VGA monitor was active. Otherwise, if just one, the plugged-in monitor was active. In both cases, the LCD also was active.

This nice and easy behavior was the case through kernel 4.3.3. With 4.4, the behavior changed so that if both monitors are plugged in, only the notebook LCD is active. Neither external display is on. If I start with one displayed plugged in, it is active. If I then plug the second display in, they both blank. I use this mostly as a desktop replacement, and rebooting is a serious pain now, because I have to jiggle the cables or open the display.

There are other behavioral changes that are equally bad, but this is the gist.

In X, I use xrandr to activate the displays as needed.

Is there some way to specify which of LCD/VGA/HDMI to output to from the console without X?

This snippet from the KMS wiki page indicates that it is possible.

$ for p in /sys/class/drm/*/status; do con=${p%/status}; echo -n "${con#*/card?-}: "; cat $p; done
DP-1: disconnected
HDMI-A-1: disconnected
LVDS-1: connected
VGA-1: connected

I had kept my kernel version frozen for a long time to preserve the old behavior. But I just suffered a SSD crash and had no backup of the old kernels for my new installation on a replacement drive. Thus the plea for help.

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#2 2016-11-30 08:59:54

Slithery
Administrator
From: Norfolk, UK
Registered: 2013-12-01
Posts: 5,776

Re: KMS Kernel Mode Setting problem on notebook boot.

Although not recommended, until you find a solution you could always install an old kernel from the ALA.


No, it didn't "fix" anything. It just shifted the brokeness one space to the right. - jasonwryan
Closing -- for deletion; Banning -- for muppetry. - jasonwryan

aur - dotfiles

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#3 2016-11-30 09:30:53

sweisman
Member
Registered: 2008-05-20
Posts: 42

Re: KMS Kernel Mode Setting problem on notebook boot.

Thanks for the tip. I will do that for now. But at this point, after having been stuck on this old kernel for a year, I'd like to update. There must be some way to do do what I want.

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