The purpose of the oprofile.ipc patch is to:
 - Add in the OProfile daemon some form of IPC capability.
 - Use this IPC mechanism to describe module mappings of jitted kernel
   code. Have opreport show performance counters within such code.

NOTES:
------

 - Discussions about this work can be found at:

   http://sourceforge.net/mailarchive/forum.php?thread_id=5907057&forum_id=3252

 - *.old* patches are older patch backups. Don't use them.



BUGS:
-----

 - This patch applies against 0.8.2cvs. It is created from a checkout
   on 11/8/2004.

 - This work is currently experimental. It has been verified that
   module mappings for JIT code are added, and samples files for them
   are created using a 2.4 kernel. However opreport shows output in
   the format:
 
00000000 53        0.0621  sys_brk_jit            (no symbols)
  00000002 4         7.5472
  00000012 6        11.3208
  0000001f 8        15.0943
  00000023 1         1.8868
  00000024 7        13.2075
  0000002a 27       50.9434

instead of...

c013fd6c 51        0.0597  vmlinux                  path_walk
  c013fd6c 27       52.9412
  c013fd6e 7        13.7255
  c013fd73 1         1.9608
  c013fd7f 10       19.6078
  c013fd81 1         1.9608
  c013fd86 5         9.8039

  daemon/opd_ipc_commands.c(opd_ipc_process_command_add_mapping) is
  most likely the function to blame for not getting output in offsets
  rather than absolute addresses. This appears to happen with all
  loadable modules in OProfile anyway.

 - The patch does not include autoconf macros for detecting presence
   of pthreads, since using pthreads is still under debate. John Levon
   proposed using select()/read() rather than a multithreaded daemon.

 - Could probably reuse routines from libutil/op_fileio.h to read from
   the pipe and improve daemon/opd_ipc.c(opd_ipc_pipe_read_thread)
   with op_try_open_file()

 - There's no locking at all when a module mapping is added. This is
   definitely wrong! Who knows what should be locked. The modules
   database at a minimum.

 - Removing the named pipe file does not seem to work.

 - I had a hard time debugging this, since calling opd_create_module()
   within opd_ipc_commands.c resulted the 2.6 version being called,
   while all other modules where loaded using the liblegacy(2.4)
   version. I had to rename opd_create_module() accordingly. This may
   not be the right thing to do.

 - There are some extra verbprintf()s currently used for debugging
   that should be removed if this work is accepted by the OProfile team.


CHANGELOG ENTRY:
----------------

 Kristis Makris <kristis.makris@asu.edu>

 Implemented an IPC capability in the OProfile daemon using a named
 pipe. A thread (using pthreads) blocks reading daemon control
 commands (in text-based format) from the pipe. The only command
 currently accepted is in the format:

 add_mapping my_jitted_code_module_name 0xstart_address 0xend_address

 Thus one can add mappings while oprofiled is running by executing:

 $ echo add_mapping sys_brk_jit 0xdac4b5e0 0xdac4b610 > /var/lib/oprofile/oprofiled.ipc"

 Added some very basic documentation in the internals document of the
 IPC feature.

 daemon/oprofiled.c(main): Initialize IPC
 daemon/opd_ipc.c: IPC implementation using a named pipe
 daemon/opd_ipc_commands.c: Handling of daemon control commands send through the pipe.
 daemon/liblegacy/init.c(opd_24_exit): Cleaning up IPC.
 daemon/liblegacy/init.c(opd_sigterm): Cleaning up IPC.
 daemon/init.c(opd_26_exit): Cleaning up IPC.
 daemon/init.c(opd_sigterm): Cleaning up IPC.
 daemon/liblegacy/opd_kernel.c(opd_create_module_24): Renamed from opd_create_module().
 daemon/liblegacy/opd_kernel.c(opd_handle_module_sample): Reread module mapping commands provided through IPC.
 daemon/liblegacy/opd_kernel.c(opd_add_kernel_map): Reread module mapping commands provided through IPC.

 daemon/liblegacy/opd_kernel.h(opd_create_module_24): Renamed from opd_create_module().
 daemon/liblegacy/opd_kernel.c(struct opd_module): Moved into daemon/liblegacy/opd_kernel.h so that daemon/opd_ipc_commands.c(opd_ipc_process_command_add_mapping) can use it.
 daemon/liblegacy/opd_kernel.c(opd_find_module_by_name): Minor grammar changes.
 daemon/opd_kernel.c(opd_create_module_26): Renamed from opd_create_module().
 daemon/opd_kernel.h(opd_create_module_26): Renamed from opd_create_module().
 daemon/opd_trans.c(code_module_loaded): Reread module mapping commands provided through IPC.