[PLUG] X, xorg.conf.d, etc.

King Beowulf kingbeowulf at gmail.com
Sat Mar 21 20:21:12 UTC 2015


On 03/21/2015 08:42 AM, Keith Lofstrom wrote:
> --- The ask ---
> 
> The X window graphics system is evolving, the man pages and 
> howtos and tutorials I can find are not keeping up.  Where are
> some recent well written introductions to X, debugging, etc?
> 

That's odd.  Ubuntu, Gentoo, Arch, Fedora and some others have updated
their wikis in the past year - some THIS YEAR (not that anything changes
very much).  Not bad for a bunch on unpaid volunteers.

> --- explanation ---
> 
> * Irrelevant gripe, why I cannot "just google it":
> 
> Google (and DuckDuckGo) no longer generate de-novo query 
> directed search results, but seem to pick a precomputed set from
> prior similar (in their opinion) searches, resulting in a crapton
> of irrelevance, with filtering words ignored.  Hence, back to 
> the preGoogle "human search engine".

Your search-fu is weak, Grasshopper.  Ether search engine will at least
point you to "read the manpages" as well as numerous wikis, forums and
tutorials, with Google doing a bit better job.

> 
> * I've got three X problems to debug:
> 
> 0) I want to increase the debugging level of the Xorg.0.log file.
> While the file contains a lot of useless crap (the modeline list
> over and over again), it does not provide vital stuff for debug
> (like which modeline it is actually using).

Not crap, the repeats are from autodetection, and yes the actual modlne
selected is in there - how it is displayed may differ a bit between teh
different intel chipsets .  I specify my monitor capabilities in
xorg.conf and don't see that stuff.

>From 'man Xorg" you can try increasing the log level (no display
manager, ie boot into CLI)

startx -- -logverbose 5  (default is 3)

or in xorg.conf (see man xorg.conf):

Section "Device"
...
    Option         "ModeDebug" "true"
...
EndSection

Google searches:
http://www.x.org/wiki/FAQVideoModes/
http://www.x.org/archive/X11R7.7/doc/man/man5/xorg.conf.5.xhtml
*** http://www.x.org/releases/X11R7.7/doc/

You can also use 'xrandr --query' to determine your current modeline and
which ones are available/supported.

The only time you will need to create a custom modeline is for older
non-EDID, or special unique, monitors and antique GPUs. Otherwise,
simply specifying monitor's resolution and refresh is enough.

More search results:
http://www.phoronix.com/scan.php?page=article&item=927&num=2
http://www.arachnoid.com/modelines/

Finally, modelinees (timings etc) are for analog VGA monitors only.
digital HDMI, DVI, are a different beast.

> 
> 1) The intel driver /usr/lib64/xorg/modules/drivers/intel_drv.so 
> seems to add about 5% to the monitor EDID pixel clock rate (I 
> suspect it is an M to Mi confusion).  I want to tell it to use
> one of the slower clock options it lists in the (repeated) 
> modeline list. 

See above and check your intel chipset support:
http://www.x.org/wiki/IntelGraphicsDriver/

> 
> 1a) This is complicated on one machine because I occasionally
> switch on and off a second monitor, though that does not seem
> to be directly correlated to my current problems - it does make
> kluging more complicated.

Should have no effect, other than filling up you X logs with EDID and
autodetect info.

> 
> 2) Particular to one of the machines (with builtin intel HD 
> graphics), when the display goes into timeout lock, and perhaps
> other times, it generates a screen full of herringbone garbage
> rather than the usual lockout message (the mouse pointer sprite
> still works).  A crtl-alt-F5 followed by ctrl-alt-F1 restores a
> readable lockout page, but my geekishness-resistant users think
> that is stupid, and so do I.  Generating a bug report without
> decent log data is difficult.

Hmmm...that pattern is the default root X window background, IIRC, with
no display manager or window manager.  Sounds like whatever DM or WM you
are using crashed.

Besides the xorg log, you may want to also check:
/var/log/messages
/var/log/syslog
/var/log/dmesg

This is not an X.org issue.

> 
> So - with some current documentation (do they still write that?)

Yes.  And print actual paper books, too.

> of the current evolving X paradigm I can debug and generate usable
> bug reports.  "The screen is messed up, trust me" will not work.
> Suggestions?

When asking for help, you may want to provide a bit more information:
Distro, kernel version, VGA or DVI,  etc.

Also, be a bit more concise.  There's a lot of fluff in your post,
though while funny in a snarky sort of way, is irrelevant to seeking
assistance, and may be off-putting to some.

> 
> Keith
> 




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