Hi,

here are three patches, two enhancing the ipipe tracer, the third
propagating the new features to Xenomai.

The tracer gains support for recording a Linux pid + a priority value.
The priority can be set to an arbitrary value (12 bit, signed), but will
typically be related to the pid. When the tracer's verbose mode is
active, it tries to resolve the pid to a task_struct and prints the
first chars of the command line followed by the priority in the related
lines.

This feature is applied to Xenomai for tracing RT-task switches and
wakeups. Kind of poor man's LTT, but with the advantage of per-function
tracing. I already used this while trying to understand my
prio-inversion issue.

Finally, the tracer is enhanced by a facility to track the currently
active ipipe domain. The field for displaying domain stall flags is
reused for this.

Some example from my Pentium-133 box:

> I-pipe frozen back-tracing service on 2.6.16.16/ipipe-1.3-05
> ------------------------------------------------------------
> Freeze: 6070092534285 cycles, Trace Points: 1000 (+10)
> 
>  +----- Hard IRQs ('|': locked)
>  |+---- <unused>
>  ||+--- <unused>
>  |||+-- Xenomai
>  ||||+- Linux ('*': domain stalled, '+': current, '#': current+stalled)
>  |||||                        +---------- Delay flag ('+': > 1 us, '!': > 10 us)
>  |||||                        |        +- NMI noise ('N')
>  |||||                        |        |
>       Type    User Val.   Time    Delay  Function (Parent)
> :    +func               -3221+   2.105  n_tty_set_room+0x8 (n_tty_receive_buf+0xe4b)
> :    +func               -3219+   2.060  kill_fasync+0x9 (n_tty_receive_buf+0xe78)
> :    +func               -3217+   1.458  __wake_up+0xe (n_tty_receive_buf+0xe97)
> :    +func               -3216+   2.421  __ipipe_test_and_stall_root+0x8 (__wake_up+0x1a)
> :    #func               -3213+   2.135  __wake_up_common+0xe (__wake_up+0x50)
> :    #func               -3211+   6.090  default_wake_function+0x8 (__wake_up_common+0x33)
> :|   #func               -3205+   2.676  __ipipe_handle_irq+0xe (common_interrupt+0x18)
> :|   #func               -3203+   2.360  __ipipe_ack_common_irq+0xa (__ipipe_handle_irq+0x80)
> :|   #func               -3200+   3.428  ipipe_test_and_stall_pipeline_from+0x8 (__ipipe_ack_common_irq+0x16)
> :|   #func               -3197+   4.511  mask_and_ack_8259A+0xb (__ipipe_ack_common_irq+0x3f)
> :|   #func               -3192+   2.571  __ipipe_dispatch_wired+0xe (__ipipe_handle_irq+0x8a)
> :|  #*func               -3190+   2.766  xnintr_irq_handler+0xb (__ipipe_dispatch_wired+0x7d)
> :|  #*func               -3187+   4.902  rt_irqbench_task_irq+0xa [xeno_irqbench] (xnintr_irq_handler+0x24)
> :|  #*func               -3182+   3.451  rtdm_event_signal+0x9 (rt_irqbench_task_irq+0x46 [xeno_irqbench])
> :|  #*func               -3179+   3.796  xnsynch_flush+0xe (rtdm_event_signal+0x2d)
> :|  #*func               -3175+   3.263  xnpod_resume_thread+0xe (xnsynch_flush+0x76)
> :|  #*[  922] irqloop 99 -3171+   4.375  xnpod_resume_thread+0x48 (xnsynch_flush+0x76)
> :|  #*func               -3167+   2.992  xnpod_schedule+0xe (rtdm_event_signal+0x36)
> :|  #*func               -3164+   2.511  rthal_irq_end+0x8 (xnintr_irq_handler+0x41)
> :|  #*func               -3162+   3.969  enable_8259A_irq+0x9 (rthal_irq_end+0x2e)
> :|  #*func               -3158+   2.511  xnpod_schedule+0xe (xnintr_irq_handler+0x5f)
> :|  #*[    0] swapper  0 -3155+   8.669  xnpod_schedule+0x82 (xnintr_irq_handler+0x5f)
> :|  #*func               -3146+   7.766  __switch_to+0xe (xnpod_schedule+0x5e8)
> :|  #*[  922] irqloop 99 -3139+   6.992  xnpod_schedule+0x6bc (xnpod_suspend_thread+0xed)
> :|  #*func               -3132!  18.015  __ipipe_restore_pipeline_head+0x8 (rtdm_event_timedwait+0xea)
> :   +*func               -3114+   2.774  __ipipe_syscall_root+0x9 (system_call+0x20)
> :   +*func               -3111+   2.323  __ipipe_dispatch_event+0xe (__ipipe_syscall_root+0x55)
> :   +*func               -3109+   4.676  hisyscall_event+0xe (__ipipe_dispatch_event+0x5e)
> :   +*func               -3104+   2.135  sys_rtdm_ioctl+0x8 (hisyscall_event+0x140)
> :   +*func               -3102+   2.157  _rtdm_ioctl+0xe (sys_rtdm_ioctl+0x16)
> :   +*func               -3100+   2.052  rtdm_context_get+0x9 (_rtdm_ioctl+0x1f)

Jan