xserver-multidpi/doc/dtrace
Peter Hutterer c0b0a9bce9 dix: add dtrace probes to input API
For driver debugging, it is helpful to know whether the driver has actually
submitted an event to the server. dtrace hooks can help here.

Note that GetPointerEvents and friends may also be triggered by the server
for other emulated devices, some care must be taken when analysing the
results.

Additional difficulty: proximity events have a run-time assigned type, so
this may make automatic detection a tad harder. If in doubt, go for any
event > 64 since the only two that can have that value are ProximityIn and
ProximityOut.

An example systemtap script is below:

  # Compile+run with
  #       stap -g xorg.stp /usr/bin/Xorg
  #

  function print_valuators:string(nvaluators:long, mask_in:long, valuators_in:long) %{
          int i;
          unsigned char *mask = (unsigned char*)THIS->mask_in;
          double *valuators = (double*)THIS->valuators_in;
          char str[128] = {0};
          char *s = str;

  #define BitIsSet(ptr, bit) (((unsigned char*)(ptr))[(bit)>>3] & (1 << ((bit) & 7)))

          s += sprintf(s, "nval: %d ::", (int)THIS->nvaluators);
          for (i = 0; i < THIS->nvaluators; i++)
          {
                  s += sprintf(s, "	%d: ", i);
                  if (BitIsSet(mask, i))
                      s += sprintf(s, "%d", (int)valuators[i]);
          }

          sprintf(THIS->__retvalue, "%s", str);
  %}

  probe process(@1).mark("input__event")
  {
      deviceid = $arg1
      type = $arg2
      detail = $arg3
      flags = $arg4
      nvaluators = $arg5

      str = print_valuators(nvaluators, $arg6, $arg7)
      printf("Event: device %d type %d detail %d flags %#x %s\n",
              deviceid, type, detail, flags, str);
  }

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Acked-by: Jeremy Huddleston <jeremyhu@apple.com>
2012-03-22 11:33:42 +10:00
..
.gitignore doc: add external doc references support to Xserver-DTrace 2011-05-14 11:22:17 -07:00
Makefile.am Install xml versions of specs even if HAVE_XMLTO is false 2011-06-20 08:41:52 +10:00
Xserver-DTrace.xml dix: add dtrace probes to input API 2012-03-22 11:33:42 +10:00