Red Hat Bugzilla – Bug 84944
Laptop - Lost ability to switch to/from LCD and Monitor
Last modified: 2007-11-30 17:10:31 EST
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User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20030215
Description of problem:
In Red Hat 8.0 and previous versions of Red Hat Linux my laptop was able to
switch between built-in LCD screen and external monitor with Fn-F7 key.
In Phoebe2 and Phoebe3 I noticed that I completely lost this ability. If I
change to a text console it works, but the running XFree86 session must be
completely killed in order to change from LCD to monitor or vice versa.
My laptop is a Sony Vaio FXA36, mobile Athlon with VIA KT133a chipset.
More hardware information.
Two other people on phoebe-list have said that their laptop in Phoebe can no
longer switch video output.
Version-Release number of selected component (if applicable):
It's probably a good idea to report this to firstname.lastname@example.org as well,
since I don't have any laptop hardware, it would be very difficult for me
to investigate this matter personally. I will keep an eye peeled for
bugfixes however, and provide test packages to try if a patch becomes
You might want to attach your config file and log file in case they come
Created attachment 90339 [details]
XF86Config from Sony Vaio FXA36 laptop
Created attachment 90340 [details]
XFree86.0.log from Sony Vaio FXA36
Created attachment 90342 [details]
XFree86-188.8.131.522-20030220.1 log for Packard Bell Chrom@ (ATI RAGE Mobility M1)
I'm unable to switch between LCD and external monitor on my computer. Video
output is always displayed simulatenously on both the built-in LCD panel and
the external monitor.
Pressing Fn+F3 to switch output causes a little flash but video output still
goes to both devices.
Created attachment 90343 [details]
XF86Config for Packard Bell Chrom@ (ATI RAGE Mobility M1)
NOTE: I have disabled XFS support for X11 but the reported problem is
reproducible with standard XFS-based font support and current config.
Date: Tue, 25 Feb 2003 02:31:55 -0500 (EST)
From: Leif Delgass <email@example.com>
Content-Type: TEXT/PLAIN; charset=US-ASCII
Subject: Re: Laptop - Lost ability to switch between LCD and Monitor
I think it's more of a feature than a bug. ;) Based on your X log in the
bugzilla bug, your laptop has a Rage Mobility mach64 chip. Display
switching via the BIOS (with the X server's VT active) was disabled for
mach64s with dual-CRTCs in XFree86 184.108.40.206:
(#105 in the CHANGELOG)
My guess is that allowing BIOS-initiated display switches with the X
server active could cause problems because the driver's cached register
state might not be valid after the display switch. For example, if you
switch from the LCD to the CRT, the driver would continue to program the
card as if the LCD were still active, when in fact the BIOS has changed
the card's state out from under the driver.
In the revision above, the feature bit for display switching is re-enabled
when switching away to a text console VT (assuming it was enabled in the
BIOS at server startup), which is why the display switching works there,
but the driver disables the feature bit and restores its cached state when
switching back to the X server.
> Pressing Fn+F3 to switch output causes a little flash but video output
> still goes to both devices.
My laptop is Fn+F7, but I too have this screen flash when it attempts to switch
video output and fails.
> I think it's more of a feature than a bug. ;) Based on your X log in the
> bugzilla bug, your laptop has a Rage Mobility mach64 chip. Display
> switching via the BIOS (with the X server's VT active) was disabled for
> mach64s with dual-CRTCs in XFree86 220.127.116.11:
Does this mean we forever lost this ability? It seemed to work in previous
releases without crashing, though based upon that description I can see
potential for problems...
I'm inclined to leave the decision up to the ATI driver maintainer
personally. I suppose there might be a better solution, but I'm not
inclined to look for one without having any of this hardware to work
with. The ATI driver maintainer or ATI themselves IMHO make the call
I'll leave this open for now to see what creeps up though.
Unfortunately, this has always been a problem with hotkey switching
interacting with the saved register state. There are no easy
solutions to this problem since it is BIOS specific. There are a few
laptops that correctly save and restore all state, but most do not.
I would suggest that you file this bug in the X.Org bugzilla
(http://bugs.freedesktop.org using the xorg component), if it still
doesn't work with the current release so that it can be tracked.
Fixing the problem in a generic way will require involvement of
several components working together, which would be need to be
coordinated with X.Org.