We have created an mdb module and some simple shell script wrappers

that can be used to retrieve various information from a running X server

or a X server core dump.

Currently available information includes:

 - a list of the clients connected to an X server, including for each one:

	- the sequence number of the last request it sent

	- in the case of most local clients, their process id

 - a list of the input devices connected to an X server and if any

	active grabs are applied to them, which client has done so.

 - if a server grab has been done, the id of the client that has the grab.

Scripts

-------

The simple shell script wrappers are all delivered in /usr/demo/Xserver/mdb

All of these scripts can be run on either a running process or a core file.

To use these scripts on a running Xserver, specify the process id with the

-p flag, such as "list_Xserver_clients -p 32999".   To use on a core file,

simply provide the core file as an argument.   (The command line arguments

are passed through to mdb, see the mdb(1) man page for more details.)

To use on a running Xorg server, you will need to run as root, due to the

restrictions

- list_Xserver_clients

This can be useful for trying to figure out which client is

responsible for the reads and writes you see to a certain file

descriptor in a truss and similar debugging activities. The sequence

number will basically be a count of the number of requests an X client

has sent during its lifetime.

You will get output like this:

max_clients = 1024

CLIENT SEQUENCE #  FD  PIDS

    0           0  -1 9719

    1           8  15  ??? - NULL OsCommPtr->process

    2           9  16 9721

    4           8  18  ??? - NULL OsCommPtr->process

    5          17 ??? - NULL ClientPtr->osPrivate

    6          14  19 9763

    7          71  20 9814

    8          13  21 9819

    9          17  22 9836

   10      501747  23 9837

   11         147  24 9837

   12          11  25 9837

   13        9676  26 9843

   14       38347  27 9843

   15          11  28 9843

   16       13251  29 9846 9857 9861 9871

   18        5299  31 9847 9891 9894 9900 9904 9922

   19        2397  32 9879

   21          11  34 9879

   23    34389507  36 9885

1342  /usr/dt/bin/dtlogin -daemon

  9719  /usr/X11/bin/Xorg :0 -depth 24 -nobanner -auth /var/dt/A:0-epayvc

  9721  /usr/openwin/bin/fbconsole -d :0

  9720  /usr/dt/bin/dtlogin -daemon

    9741  /bin/ksh /usr/dt/bin/Xsession

      9819  /usr/dt/bin/sdt_shell -c unsetenv _ PWD;             unsetenv DT;

        9821  -csh -c unsetenv _ PWD;             unsetenv DT;      setenv DISP

          9837  /usr/dt/bin/dtsession

            9843  dtwm

            9846  /usr/dt/bin/dtterm -session dtb2aitb -C -ls

              9857  -csh

              9861  -csh

              9871  -csh

            9847  /usr/dt/bin/dtterm -session dtP2aqtb -C -ls

              9891  -csh

              9894  -csh

              9900  -csh

              9904  -csh

              9922  -csh

            9879  dtfile -session dtqRaOFb

              9949  dtfile -session dtqRaOFb

            9885  sdtperfmeter -f -H -t cpu -t disk -s 1 -name fpperfmeter

9836  /usr/dt/bin/ttsession

The output at the end comes from ptree. From this example we can see

the busiest client in this CDE session has been sdtperfmeter since it

has sent 34389507 X requests in order to update the performance meter

once a second. (This session was running for 6 days before this output

was taken.)

- list_Xserver_devicegrab_client

This lists all the input devices known to the Xserver and if they have

been grabbed by any clients, which client holds an active grab.

For instance, on a machine where the xterm "Secure Keyboard" menu item

was chosen to grab the keyboard:

 # list_Xserver_devicegrab_client -p 6072

  Device "Virtual core pointer" id 2:

    -- no active grab on device

  Device "Virtual core keyboard" id 3:

    -- active grab 5e00000 by client 47

  Device "Virtual core XTEST pointer" id 4:

    -- no active grab on device

  Device "Virtual core XTEST keyboard" id 5:

    -- no active grab on device

  Device "mouse" id 6:

    -- no active grab on device

  Device "hotkey" id 7:

    -- no active grab on device

  Device "keyboard" id 8:

    -- no active grab on device

You can then use list_Xserver_clients to find out what client 47 is:

  CLIENT SEQUENCE #  FD  PIDS

   [...]

     47        3378  78 8936

   [...]

      8936  xterm

- list_Xserver_servergrab_client

This script checks a variable in the X server to determine if a server

grab has been done, and if so which client has done it.

Debugging with mdb

------------------

The mdb module can also be used directly in an mdb debugging session

on either a live server or a core file.  The module is delivered in

/usr/lib/mdb/proc as Xorg.so, Xvfb.so, Xephyr.so and Xvnc.so so that

it should be automatically loaded when mdb attaches to a process or

core of any of those programs.

Two sets of dcmds are provided, each with a "walker" which simply

iterates over the entries in the X server internal tables, and a

command that prints the information for each entry.

The commands currently provided are:

	::client_pids - prints information about a ClientRec entry

	   in the X server's array of currently connected X clients.

	::inputdev_grabs - prints information about a DeviceIntRec entry

	   in the X server's list of currently connected input devices.

The walkers to iterate over the lists of these structures in the X server are:

	::client_walk - walks the array of ClientRec entries stored in the

		global array "clients", from 0 to the value of the global

		variable "currentMaxClients"

	::inputdev_walk - walks the linked list of DeviceIntRec entries

		starting at the entry stored in the global variable "InputInfo"

You can run them like this:

# mdb -p 9719

Loading modules: [ Xorg ld.so.1 libc.so.1 libproc.so.1 libnvpair.so.1 libuutil.so.1 libavl.so.1 libsysevent.so.1 ]

> ::walk client_walk

max_clients = 1024

1b7db8

1b7dbc

1b7dc0

[...]

> 1b7dc0  ::client_pids

CLIENT SEQUENCE #  FD  PIDS

    2           9  16 9721

If you run one of the commands (such as ::client_pids) without an address in

front, it will automatically call the associated walker to list the

information for all the entries in the list.

http://hub.opensolaris.org/bin/view/Community+Group+mdb/

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