Bug 245741 - Unable to get more than 800x600 screen resolution with new FC6 kernel
Summary: Unable to get more than 800x600 screen resolution with new FC6 kernel
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 6
Hardware: i686
OS: Linux
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2007-06-26 13:02 UTC by Mike Cohler
Modified: 2007-11-30 22:12 UTC (History)
1 user (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2007-07-27 20:39:25 UTC

Attachments (Terms of Use)
xorg log with new kernel (57.22 KB, application/octet-stream)
2007-06-26 13:03 UTC, Mike Cohler
no flags Details
xorg log with new kernel - text file (57.22 KB, text/plain)
2007-06-26 13:04 UTC, Mike Cohler
no flags Details
xorg log with old kernel - text file (60.16 KB, text/plain)
2007-06-26 13:05 UTC, Mike Cohler
no flags Details
/var/log/messages (122.77 KB, text/plain)
2007-06-26 13:11 UTC, Mike Cohler
no flags Details
xorg.conf as autogenerated by the system (566 bytes, text/plain)
2007-06-27 10:04 UTC, Mike Cohler
no flags Details

Description Mike Cohler 2007-06-26 13:02:59 UTC
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
2. Re-boot
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.

Comment 1 Mike Cohler 2007-06-26 13:03:00 UTC
Created attachment 157891 [details]
xorg log with new kernel

Comment 2 Mike Cohler 2007-06-26 13:04:03 UTC
Created attachment 157892 [details]
xorg log with new kernel - text file

Comment 3 Mike Cohler 2007-06-26 13:05:10 UTC
Created attachment 157893 [details]
xorg log with old kernel - text file

Comment 4 Mike Cohler 2007-06-26 13:11:04 UTC
Created attachment 157894 [details]

Comment 5 Chuck Ebbert 2007-06-26 21:07:30 UTC
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

   HorizSync 31-80
   VertRefresh 56-75

to the "monitor" section of /etc/X11/xorg.conf.

Comment 6 Mike Cohler 2007-06-27 10:04:48 UTC
Created attachment 157988 [details]
xorg.conf as autogenerated by the system

Comment 7 Mike Cohler 2007-06-27 10:06:45 UTC
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
section containing:

Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "Monitor Vendor"
        ModelName    "Monitor Model"
        HorizSync    31-80
        VertRefresh  56-75

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?

Comment 8 Chuck Ebbert 2007-06-27 20:53:15 UTC
I'm not an Xpert but I think it needs to have

     Monitor "Monitor0"

added to the Screen section?

Comment 9 Chuck Ebbert 2007-06-27 20:56:33 UTC
Can we get a copy of boot messages from the old kernel?

Comment 10 Mike Cohler 2007-06-28 07:57:59 UTC
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

Comment 11 Mike Cohler 2007-07-02 12:03:53 UTC
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
this machine.

Comment 12 Mike Cohler 2007-07-02 16:23:25 UTC
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?

Comment 13 Adam Jackson 2007-07-27 20:39:25 UTC
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.

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