Subject: Re: how to turn off display? (wsdisplay0 at vesafb0)
To: Jared D. McNeill <>
From: Jeremy C. Reed <>
List: tech-kern
Date: 08/05/2006 11:25:00
> > Can someone point me to a tool or code for turning off a display or
> > powering down a laptop screen?
> > 
> > I am using NetBSD/i386 3.99.21 with:
> >  wsdisplay0 at vesafb0 kbdmux 1: console (fb, vt100 emulation)
> > 
> > And Xorg's wsfb(4) driver.
> ``options VESAFB_PM'' in your kernel will enable the WSDISPLAYIO_SVIDEO 
> and WSDISPLAYIO_GVIDEO ioctl implementations, which wsfb(4) should use 
> when it decides to blank the display.

Thanks. With that option, now my X blank will turn off the screen.

But now I need to figure out how to turn the screen back on.

> It currently defaults to 'standby' mode; you will need to modify 
> vesafb.c (see vesafb_svideo) if you want to attempt another mode that 
> your video BIOS supports -- possible values are 'standby', 'suspend', 
> 'off', and 'reduced_on'.
> YMMV, as I've seen certain systems simply reset when I attempt to call the
> video PM BIOS function.

I guess my box was down, as I did: "shutdown -r +1" in one window and 
blanked with "xset s 1" in another. And my system never came back up. (I 
didn't try pinging it or connecting to it from outside.)

Any ideas on how I can troubleshoot this "video PM BIOS function"?