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Old 11-24-2008, 04:10 AM   #1
fedix
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Registered: Oct 2005
Location: Mpumalanga, South Africa
Distribution: Fedora / CentOS 5 / Ubuntu
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Cant login after changing VGA resolution


I've installed CentOS 5 on a HP Desktop PC with a LG 17" Flatron (L1718S) LCD monitor. By default, Centos set the resolution to 800x600.

Changed the resolution to 1024x768, logged off and logged on again, no problem. However, the power dipped and after the PC rebooted, the LCD monitor doesn't show the X86 GUI logon screen, only reporting "Out of Range" 45.1kHz / 43Hz".

I've tried to boot by intercepting grub and added "VGA=787" to the kernel... boot line, with no success.

Any help on getting my logon screen back / resolving the problem?
 
Old 11-24-2008, 08:23 AM   #2
rylan76
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Registered: Apr 2004
Location: Potchefstroom, South Africa
Distribution: Fedora 17 - 3.3.4-5.fc17.x86_64
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Strange... but I one had something similar with an old CRT under FC3. You also have EXACTLY the same LCD monitor I currently use on my FC6 system on a NVidia geForce 7950GT with the 2.6.18.1 kernel at 1152x864...

The old CRT of course, did not say "out of range" or anything, it just buzzed and stayed pitch black as the card (back then I had an old Nvidia 6600 or something) tried to drive it too "high".

What I did back then to get my old CRT working with X was to use my distro's "rescue disk" to get into a terminal after booting off the rescue disk. Then I edited the following file:

/etc/inittab

in which I set the following from "5" to "3". 5 = runlevel 5 = start x-windows, 3 = runlevel 3 = text mode.

[/etc/inittab]
Code:
#
# inittab       This file describes how the INIT process should set up
#               the system in a certain run-level.
#
# Author:       Miquel van Smoorenburg, <miquels@drinkel.nl.mugnet.org>
#               Modified for RHS Linux by Marc Ewing and Donnie Barnes
#

# Default runlevel. The runlevels used by RHS are:
#   0 - halt (Do NOT set initdefault to this)
#   1 - Single user mode
#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
# 
id:5:initdefault:

# System initialization.
si::sysinit:/etc/rc.d/rc.sysinit

l0:0:wait:/etc/rc.d/rc 0
l1:1:wait:/etc/rc.d/rc 1
l2:2:wait:/etc/rc.d/rc 2
l3:3:wait:/etc/rc.d/rc 3
l4:4:wait:/etc/rc.d/rc 4
l5:5:wait:/etc/rc.d/rc 5
l6:6:wait:/etc/rc.d/rc 6

# Trap CTRL-ALT-DELETE
ca::ctrlaltdel:/sbin/shutdown -t3 -r now

# When our UPS tells us power has failed, assume we have a few minutes
# of power left.  Schedule a shutdown for 2 minutes from now.
# This does, of course, assume you have powerd installed and your
# UPS connected and working correctly.  
pf::powerfail:/sbin/shutdown -f -h +2 "Power Failure; System Shutting Down"

# If power was restored before the shutdown kicked in, cancel it.
pr:12345:powerokwait:/sbin/shutdown -c "Power Restored; Shutdown Cancelled"


# Run gettys in standard runlevels
1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn:/sbin/mingetty tty2
3:2345:respawn:/sbin/mingetty tty3
4:2345:respawn:/sbin/mingetty tty4
5:2345:respawn:/sbin/mingetty tty5
6:2345:respawn:/sbin/mingetty tty6

# Run xdm in runlevel 5
x:5:once:/etc/X11/prefdm -nodaemon
Make the change on the line that says

id:5:initdefault:

and change it to

id:3:initdefault:

save the file, quit your rescue mode and restart the system.

You should now at least have terminal access so you can examine or hack your xorg.conf to get it to use a lower resolution.

To test if you x-windows can start up while you are in runlevel 3 as detailed above, do

startx

in the text terminal.

X will either start, or you LCD will again go into the "unreachable" screen. If it does, simply pres CTRL+ALT+BACKSPACE

to kill the X server - you should be dumped right back into text mode - and then try to edit your xorg.conf again.

Editing xorg.conf by hand is an art form on its own, I can't help you there really. Most likely whatever you did made an automatic change in your xorg.conf that your LCD does not like much. For example, here is an xorg.conf off my older FC3 system:

Code:
# XFree86 4 configuration created by pyxf86config

Section "ServerLayout"
	Identifier     "Default Layout"
	Screen      0  "Screen0" 0 0
	InputDevice    "Mouse0" "CorePointer"
	InputDevice    "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"

# RgbPath is the location of the RGB database.  Note, this is the name of the 
# file minus the extension (like ".txt" or ".db").  There is normally
# no need to change the default.
# Multiple FontPath entries are allowed (they are concatenated together)
# By default, Red Hat 6.0 and later now use a font server independent of
# the X server to render fonts.
	RgbPath      "/usr/X11R6/lib/X11/rgb"
	FontPath     "unix/:7100"
EndSection

Section "Module"
	Load  "dbe"
	Load  "extmod"
	Load  "fbdevhw"
	Load  "glx"
	Load  "record"
	Load  "freetype"
	Load  "type1"
	#Load  "dri"
EndSection

Section "InputDevice"

# Specify which keyboard LEDs can be user-controlled (eg, with xset(1))
#	Option	"Xleds"		"1 2 3"
# To disable the XKEYBOARD extension, uncomment XkbDisable.
#	Option	"XkbDisable"
# To customise the XKB settings to suit your keyboard, modify the
# lines below (which are the defaults).  For example, for a non-U.S.
# keyboard, you will probably want to use:
#	Option	"XkbModel"	"pc102"
# If you have a US Microsoft Natural keyboard, you can use:
#	Option	"XkbModel"	"microsoft"
#
# Then to change the language, change the Layout setting.
# For example, a german layout can be obtained with:
#	Option	"XkbLayout"	"de"
# or:
#	Option	"XkbLayout"	"de"
#	Option	"XkbVariant"	"nodeadkeys"
#
# If you'd like to switch the positions of your capslock and
# control keys, use:
#	Option	"XkbOptions"	"ctrl:swapcaps"
# Or if you just want both to be control, use:
#	Option	"XkbOptions"	"ctrl:nocaps"
#
	Identifier  "Keyboard0"
	Driver      "kbd"
	Option	    "XkbModel" "pc105"
	Option	    "XkbLayout" "us"
EndSection

Section "InputDevice"
	Identifier  "Mouse0"
	Driver      "mouse"
	Option	    "Protocol" "IMPS/2"
	Option	    "Device" "/dev/input/mice"
	Option	    "ZAxisMapping" "4 5"
	Option	    "Emulate3Buttons" "yes"
EndSection

Section "Monitor"
	Identifier   "Monitor0"
	VendorName   "Monitor Vendor"
	ModelName    "PHILIPS 107S"
	DisplaySize  310	230
	HorizSync    30.0 - 71.0
	VertRefresh  50.0 - 160.0
	Option	    "dpms"
EndSection

Section "Device"
	Identifier  "Videocard0"
	Driver      "nvidia"
	VendorName  "Videocard vendor"
	BoardName   "NVIDIA GeForce FX (generic)"
EndSection

Section "Screen"
	Identifier "Screen0"
	Device     "Videocard0"
	Monitor    "Monitor0"
	DefaultDepth     16
	SubSection "Display"
		Viewport   0 0
		Depth     16
		Modes    "1152x864" "800x600" "640x480"
	EndSubSection
EndSection

Section "DRI"
	Group        0
	Mode         0666
EndSection
Note the section that reads

Code:
Section "Screen"
	Identifier "Screen0"
	Device     "Videocard0"
	Monitor    "Monitor0"
	DefaultDepth     16
	SubSection "Display"
		Viewport   0 0
		Depth     16
		Modes    "1152x864" "800x600" "640x480"
	EndSubSection
EndSection
This means that, in my case, my X-server will be limited to

1152x864

or

800x600

or

640x480

You'll probably find some preposterous resolution listed (the one that is forcing your LCD to go too "high") - so remove the highest one, save the file, try startx. If it still does not work, remove the next highest one, try startx. Keep on doing this, at some point your LCD should start up fine. (Remember, each time you get into X and it does not work, simply press CTRL ALT BACKSPACE (All at once!) to get back to the text terminal, and then try editing your xorg.conf again.

Once you have managed to gear down to a usable resolution, edit /etc/inittab again and change

Code:
id:3:initdefault:
back to

Code:
id:5:initdefault:
save the file and reboot - you should again get into gdm, and stuff should be visible...

Hope this helps.

Regards,

Last edited by rylan76; 11-24-2008 at 08:26 AM. Reason: Noted new info
 
Old 11-24-2008, 11:54 PM   #3
fedix
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Registered: Oct 2005
Location: Mpumalanga, South Africa
Distribution: Fedora / CentOS 5 / Ubuntu
Posts: 104

Original Poster
Rep: Reputation: 17
Dankie Stefan

I did what you suggested; couldn't get it right but eventually I did get something going; and exactly what I did, I can't remember exactly. However, from other forums I got the tip of changing values in xorg.conf and the ones that seems to made a difference was to raise the HorizSync values (now 40.0 - 60.5), the VertRefresh (60.0 - 80.0) and the depth to 16 colors. I also changed the Monitor name to "LCD Panel 1280x1024". This gave me at least the option to choose 1024x768 instead of the 800x600 which was the highest before the "black out".

Regards
 
Old 11-25-2008, 12:54 AM   #4
rylan76
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Registered: Apr 2004
Location: Potchefstroom, South Africa
Distribution: Fedora 17 - 3.3.4-5.fc17.x86_64
Posts: 1,552

Rep: Reputation: 103Reputation: 103
Hey! Nog 'n Suid Afrikaner! Eerste keer wat ek 'n mede vleisbraaier hier kry...

Anyway hoop jou LCD werk nou lekker. Ek is baie tevrede met my LGtjie sover.

Hoop jy geniet die Pikkewyn wereld....
 
Old 03-11-2009, 01:51 PM   #5
fedix
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Registered: Oct 2005
Location: Mpumalanga, South Africa
Distribution: Fedora / CentOS 5 / Ubuntu
Posts: 104

Original Poster
Rep: Reputation: 17
Thanks!
 
  


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