Red Hat Bugzilla – Bug 245741
Unable to get more than 800x600 screen resolution with new FC6 kernel
Last modified: 2007-11-30 17:12:08 EST
Description of problem:Ran yum update and booted to new kernel
kernel-2.6.20-1.2962.fc6. Unable to get better than 800x600, but rebooting back
to previous kernel without further change returns the screen to normal resolution.
Version-Release number of selected component (if
applicable):kernel-2.6.20-1.2962.fc6 and xorg-x11-server-Xvfb.i386 1.1.1-47.10.fc6
How reproducible:Every time
Steps to Reproduce:
1. Yum update
3. Monitor resolution is 800x600 and no better resolution is possible even if
change attempted with system-config-display
Actual results:Resolution unable to get to previously set value. If machine is
rebooted back to kernel-2.6.20-1.2952.fc6 then screen resolution returns to normal.
Expected results: Machine should display normal resolution with new kernel
Additional info:Running KDE, and hardware profile is at
xorg logs attached.
Created attachment 157891 [details]
xorg log with new kernel
Created attachment 157892 [details]
xorg log with new kernel - text file
Created attachment 157893 [details]
xorg log with old kernel - text file
Created attachment 157894 [details]
This is probably the cause:
-(II) I810(0): VESA VBE DDC read successfully
+(II) I810(0): VESA VBE DDC read failed
But why it would suddenly stop working, I don't understand.
There aren't any kernel patches in there that should have caused this...
You should be able to work around this by adding
to the "monitor" section of /etc/X11/xorg.conf.
Created attachment 157988 [details]
xorg.conf as autogenerated by the system
There was no monitor section in xorg.conf - the xorg.conf file was
autogenerated. I have attached the original file at #6. After appending a
VendorName "Monitor Vendor"
ModelName "Monitor Model"
I restarted X with the original kernel running, and this now produced the same
problem with no more than 800x600 resolution that I get with the new kernel!
Maybe the xorg.conf file needs to have other changes?
I'm not an Xpert but I think it needs to have
added to the Screen section?
Can we get a copy of boot messages from the old kernel?
Thanks Chuck - I am away from the machine at meetings all today but I will check
the xorg.conf details tomorrow and test - and will attach copies of
/var/log/messages with relevant lines tomorrow when I am back at the machine.
There is no boot.log
I added the Monitor line to xorg.conf, and the machine does boot and gives X
with the required resolution. However the normal boot progress screen is blank
apart from a message (presumably from the monitor itself) saying that the
optimum resolution is 1280x1024 which is what it should choose anyway! Clearly
it does not choose the correct resolution until X itself starts.
I will soon be installing F7 on this machine and although this seems to be a
workaround I am not sure this bug is fully resolved.
I hope that once F7 is installed and updated that this problem will not recur on
I have done a clean f7 install on this machine, and am fully yum updated running
kernel 2.6.21-1.3228.fc7 - the problem reported in this bug does not occur with
f7 on either the original kernel or the current one.
If no-one else reports further after this then I guess this bug should be closed?
There was at least one bug in ~FC6 where the kernel's vm86 call would clobber
some registers before returning to userspace, which would confuse X horribly and
usually manifest as DDC failing.
The offending code appears to be gone in F7, so, hooray.