Wacom Intuos Photo and CentOS 6

I've had a Wacom Intuos 5x4 since 1998 or so. But support for the serial protocol it used has disappeared. What's more, my tablet was getting really crusty over nearly 20 years of use. So I went and bought a Wacom Intuos Photo, which has a smaller, wider surface (which is useful given I have 2 screens) but also can use a finger instead of a pen.

Of course, the new tablet didn't work out of the box. Well, it nearly worked.

Back in the day, I patched wacom_drv for XFree86 to get it working. Things have changed greatly since then. On modern Linux, the driver is in the kernel (wacom.ko) which creates an input and event device. X.org then uses HAL to enumerate input devices and HAL also provides hints on how to configure them. The long and short is we no longer need to mess around in xorg.conf when we change hardware. However, it means it gets very hard to debug when one of those layers does something annoying.

The easy way to get an Wacom Intuos Photo, Draw, Art to work on CentOS 6 is to install the backports of linuxwacom drivers. If you are running the stock 2.6.32 kernel, everything will Just Work.

I'm using the elrepo's 4.10 kernel-ml. This gets lm-sensors working for my motherboard and removes an annoying bug with my PS/2 keyboard.

In 4.10 kernel, the wacom driver is recognizing the tablet and doing it's job : creating 3 input event IDs one for the pad, one for the stylus and one for finger touch. However, lshal is rejecting the finger touch. I traced it down to HAL_PROP_BUTTON_TYPE not being set when hald-probe-input is called. This means the stylus automatically works on X.org, but touch doesn't.

To get finger touch to work on X.org, I had to force things. First, I need to create a symlink to the finger event ID using udev, then a partial config file for X.org :

/usr/local/lib/udev/wacom-type.sh will output a short name for each device it is called on. Make sure this script is executable!

#!/bin/bash

name=$(cat /sys/$DEVPATH/device/name)
# echo "$DEVPATH=$name" >>/tmp/wacom-dev.txt

shopt -s nocasematch

if [[ $name =~ Finger ]] ; then
    echo finger
elif [[ $name =~ Pen ]] ; then
    echo pen
elif [[ $name =~ Pad ]] ; then
    echo pad
else
    echo unknown
fi

exit 0

/etc/udev/rules.d/99-wacom.rules convinces udevd to call the above when the tablet is detected. It also convinces udevd to create a symlink in /dev/input/wacom-finger. Note that I restrict to 056a:033c, which is a Wacom Intuos Draw/Photo/Art small version. You can find the USB ID of your tablet with lsusb.

#
# Will create /dev/input/wacom-finger, I hope
#
ACTION!="add|change", GOTO="my_wacom_end"
KERNEL!="event*", GOTO="my_wacom_end"

ENV{ID_VENDOR_ID}!="056a", GOTO="my_wacom_end"
ENV{ID_MODEL_ID}=="033c", PROGRAM=="/usr/local/lib/udev/wacom-type.sh", SYMLINK+="input/wacom-%c"

LABEL="my_wacom_end"

Test the above by doing udevadm control --reload-rules, unplug tablet, wait, plug in tablet, then ls -l /dev/input and you should see:

lrwxrwxrwx  1 root root      7 Mar 22 15:50 wacom-finger -> event11
lrwxrwxrwx  1 root root      7 Mar 22 15:50 wacom-pad -> event12
lrwxrwxrwx  1 root root      7 Mar 22 15:50 wacom-pen -> event10

The numbers after event will change each time you reboot or replug the tablet.

/etc/X11/xorg.conf.d/wacom.conf will finally convince X.org to use the Wacom finger event id as a touch pad.

Section "InputDevice"
    Identifier "Finger"
    Driver "wacom"
    Option "Vendor" "Wacom"
    Option "AutoServerLayout" "on"
    Option "Type" "touch"
    Option "Device" "/dev/input/wacom-finger"
    Option "Mode" "Absolute"
    Option "Touch" "on"
    Option "Gesture" "off"
#    Option "Tilt" "on"
    Option "Threshold" "20"
    Option "Suppress" "6"
    Option "USB"    "On"
EndSection

I'd like to very much thank whot and jigpu who spent an impressive amount of time helping me over IRC.

UPDATE: 24 hours later, I have found a problem with the approach. If you unplug and replug the tablet, the Finger event ID will change. And while the wacom-finger symlink will be updated, X.org will not know that it's changed and hold onto the old event ID. This means finger will no longer work after replugging the tablet, at least until you restart X.org.

UPDATE: 1 year later and kernel-ml has gone to 4.16, which won't work. 4.15.15 is the last version that does work.

Someone broke the build

One can no longer cleanly do cpan Bundle::CPAN on a fresh install of CentOS 6. Some dependencies don't install properly. I had to do the following:

cpan CPAN::Meta::YAML Parse::CPAN::Meta 
cpan Test::YAML
cpan Compress::Raw::Zlib
cpan Spiffy Test::Base
cpan Module::Metadata  CPAN::Meta Perl::OSType version
cpan Compress::Raw::Bzip2
cpan Sub::Identify
cpan SUPER
cpan Test::MockModule
cpan Bundle::CPAN

At least I didn't have to go into /root/.cpan and install things by hand.

Still more fun with MySQL

Are you prepared to go mad? If so, compare these to statments and their results:

mysql> SELECT warehouse.NUM,warehouse.date FROM warehouse JOIN sphinx ON sphinx.id = warehouse.DID WHERE sphinx.query = 'filter=tid,288215463; index=Y2015,YD2015; limit=500; maxmatches=2000; mode=all; offset=0; query=dominique; sort=extended:date desc, sNUM desc' ORDER BY warehouse.date DESC,warehouse.NUM DESC LIMIT 50;
Empty set (0.00 sec)

mysql> SELECT warehouse.NUM,warehouse.date FROM warehouse JOIN sphinx ON sphinx.id = warehouse.DID WHERE sphinx.query = 'filter=tid,288215463; index=Y2015,YD2015; limit=500; maxmatches=2000; mode=all; offset=0; query=dominique; sort=extended:date desc, sNUM desc';
+---------+------------+
| NUM     | date       |
+---------+------------+
| AT00105 | 2015-06-17 |
+---------+------------+
1 row in set (0.00 sec)

What's going on is that MySQL is asking searchd (part of Sphinx) to do a full text search on 2 indexes. It then does a join on the results. With the ordering, I get zero results. Without ordering I get the expected results.

This shouldn't be happening. This can't be happening.

But then I found the answer: The first query in the example above was a cut and paste from the query log on my dev VM. This means that MySQL had already run that query and (more importantly) cached the results. The Sphinx indexes had been updated in the meantime. But searchd can't tell MySQL to invalidate the query cache.

mysql> SELECT SQL_NO_CACHE warehouse.NUM,warehouse.date FROM warehouse JOIN sphinx ON sphinx.id = warehouse.DID WHERE sphinx.query = 'filter=tid,288215463; index=Y2015,YD2015; limit=500; maxmatches=2000; mode=all; offset=0; query=dominique; sort=extended:date desc, sNUM desc' ORDER BY warehouse.date DESC,warehouse.NUM DESC LIMIT 50;
+---------+------------+
| NUM     | date       |
+---------+------------+
| AT00105 | 2015-06-17 |
+---------+------------+
1 row in set (0.00 sec)

Sanitiy is restored.

Long and short of this is to ALWAYS use SQL_NO_CACHE when using the Sphinx plugin.

Death To Proprietary Drivers

I was working on a CentOS 6 install for work and figured "hey, I should upgrade Mustang to the latest version." Normally this means

yum upgrade
shutdown -r now

Of course that didn't work; Mustang has an APU and uses a proprietary driver from AMD for X.org. I pretty much never use Mustang's console so I didn't notice this for 2 days, when my wife complained about not being able to watch Lost.

After much futzing, I find the error message: symbol lookup error: /usr/lib64/xorg/modules/drivers/fglrx_drv.so: undefined symbol: GlxInitVisuals2D. This means AMD's driver is doing something stupid. I of course can't compile it nor fix it. I tried to download the latest driver, but that refused to install. Curse swear, google google and then I found it.

rpm -ivh http://elrepo.org/linux/elrepo/el6/x86_64/RPMS/elrepo-release-6-6.el6.elrepo.noarch.rpm
rpm -e fglrx64_p_i_c-12.104-1 --nodeps
yum -y install fglrx-x11-drv-32bit fglrx-x11-drv kmod-fglrx
aticonfig --initial

First line installs ELRepo, which you might already have. Second line removes the previous drivers, which conflict with the new ones. The --nodeps is because Adobe really wants OpenGL installed. Third line is the important one, it installs the new drivers and does all the magic to get them working. Yes, the X.org driver needs to install a kernel module. Last line just makes sure that Xorg.conf is set up properly. I'd been playing around in it to try to get it to work.

So Death to Proprietary Drivers! And long live the guys at ELRepo!

CentOS X .xsession

Further annoyances with CentOS 6. It now uses .xsession as the last resort. The work around is to add the following lines to /etc/X11/xinit/Xsession. Put them just after the line that sources /etc/X11/xinit/xinitrc-common

if [ -x "$HOME/.xsession" ]; then
    exec -l $SHELL -c "$CK_XINIT_SESSION $SSH_AGENT $HOME/.xsession"
fi

Yes, there's probably a smarter way of doing it. But I don't want to bother tracking it down.

CentOS 6 X problems

First off, 6.4 came out and I didn't notice.

Second off, while setting up my new Laptop (Nicko, an IBM t61) for development, I managed to mess up Xorg. The error messages are

[ 25469.587] [dix] Could not init font path element catalogue:/etc/X11/fontpath.d, removing from list!
[ 25469.587] [dix] Could not init font path element built-ins, removing from list!
[ 25469.587] 
Fatal server error:
[ 25469.587] could not open default font 'fixed'

A quick fix is just yum -y upgrade. But given this would push me to 6.4 (aka a lot of downloading), a smaller fix was required. I found the following got the job done. I strongly suspect the libXfont is all that is required. YMMV

wget ftp://ftp.muug.mb.ca/mirror/centos/6.4/os/x86_64/Packages/xorg-x11-drv-modesetting-0.5.0-1.el6.x86_64.rpm
sudo rpm -Uvh xorg-x11-drv-modesetting-0.5.0-1.el6.x86_64.rpm
sudo yum install pixman pixman-devel libXfont -y
sudo yum groupinstall Desktop -y

UPS and power conditioning

If you have a server or any computer that is important, it needs an UPS. Something large enough for 5-10 minutes of power outage. But it is not enough to just plug the power into the UPS. You must also plug into UPS data port. And set up the software that will allow the computer to detect the power outage and shutdown before the battery runs out.

This is non-negotiable.

Not doing this risks you showing up Monday morning and not getting any work down while an admin drives 100 km to fix a problem.

And if you have any piece of important electronic equipment, you'll want a filter. And no the fuse on your power bar doesn't count.