A Thread Debug Interface (TDI)

gdb-tdi is an enhancement of the popular gdb debugger for extensive thread debugging. It handles FSU Pthreads, MIT Threads and LinuxThreads under SunOS 4.1.x, Solaris 2.x and Linux 2.x. You can download binaries (ready to run) or sources (to compile) below.

Calling the Thread-aware Debugger

gdb-tdi <filename>

New Thread Debugging Commands of the GDB

ptattach <Thread ID>	ptattach continues the application and stops as soon as the specified thread is executed. After ptattach all subsequent calls to step, next , stepi, nexti and break are implicitly bound to the control flow of the specified thread. ptattach can be used to observe a specific thread instead of thread hopping. After ptattach all breakpoint sassociated with other threads than the specified one ar disabled until detaching it.
ptdetach	ptdetach as the name says detaches the formerly attached thread. It enables the temporarily disabled breakpoint sfor the attached thread. All threadspecific breakpoints implicitly produced by applying break in attached mode will remain. ptdetach is automatically executed at program restart.
info pthreads	info pthreads is the small but powerfull brother of the old UNIX ps command. All thread infos are shown by info pthreads.
info pmutex	mutex infos (type it and see)
info pcond	condition variable info (type it and see)
tdi <TDI Query>	tdi is the current direct user interface to the TDI. You can specify TDI queries and see the result. The input and output is a, little bit strange now, but you are welcome to improve the quality of this feature (the patch is free software). All must be given as hexadecimal or decimal. It would be very useful to input program variables instead of values.
break <Location> pthread <Thread-ID>	This breakpoint will be reached (visible to you), if the desired thread hit it.
step, stepi,next, stepi (are threadspecific after ptattach)	In attached mode all these commands return in the same thread control flow as selected before executing it.
break (is threadspecific after ptattach)	In attached mode all breakpoints are automatically set for the attached thread.
ptsuspend <Thread List>	The desired threads will suspend their execution.
ptresume <Thread List>	The desired threads will resume their execution.
continue -cs	Continues the program until the next context switch happens. The old and the new thread are displayed. All active breakpoints are temporarily disabled until context switch completed.
continue -addcs	Continues the program until the next context switch happens. The old and the new thread are displayed. All active breakpoints remain active.

gdb-tdi binary release for FSU Pthreads

• Download FSU Pthreads
• unpack: tar xzf pthreads.tar.gz
• compile and choose your OS: cd threads/src ; ./configure
• test: cd .. ; mkdir tests
• create file create_thread.c in tests
• compile and link:
  • Linux 2.x: gcc -I$threads/include -o create_thread create_thread.c $threads/lib/libgthreads.a $threads/lib/libmalloc.a -rdynamic -ldl -g
  • Solaris 2.x: gcc -I$threads/include -o create_thread create_thread.c $threads/lib/libgthreads.a $threads/lib/libmalloc.a -ldl -laio -g
  • SunOS 4.1.x: gcc -I$threads/include -o create_thread create_thread.c $threads/lib/libgthreads.a $threads/lib/libmalloc.a -ldl -g
• only SunOS 4.1.x: setenv LD_LIBRARY_PATH /usr/local/lib/:$LD_LIBRARY_PATH
• run: ./create_thread
• debug: gdb-tdi create_thread
  POSIX Threads Library is TDI aware.
  [Kernel Threads : User Level Threads] = [1:N] i.e. FSU, MIT
  Signal used for scheduling: 14
  
  • break main
  • run
  • info pthreads
    Id Pid Addr Prio entry entry_arg MBO CVWF State RState
    1 4409 0x806a000 101 fd_server (0xfd ) - 1 BLOCK C [0x610]
    2 4409 0x8065000 0 main (0x0 ) - - RUNNING [0x209]
    
  • break 6
  • continue
  • info pthreads
    Id Pid Addr Prio entry entry_arg MBO CVWF State RState
    3 4409 0x8071000 0 new_thread (0x804bad0 ) - - RUNNING [0x208]
    1 4409 0x806a000 101 fd_server (0xfd ) - 1 BLOCK C [0x610]
    2 4409 0x8065000 0 main (0x0 ) - - BLOCK O [0x611]
    
  • ptstack 2
    Thread 2: sp: 0xbffff7a4 pc: 0x804d4ad
    #0 0x804d4ad in pthread_join ()
    #1 0x804bb24 in main () at create_thread.c:33
    
  • ptstack 3
    Thread 3: sp: 0x80750b0 pc: 0x804bae6
    #0 new_thread (arg=0xbffff7b4) at create_thread.c:23
    #1 0x804be31 in pthread_body ()
    #2 0x0 in ?? ()
    
  • continue -cs
    context switch [OldID 3] -> [NewID 2]
  • info pthreads
    Id Pid Addr Prio entry entry_arg MBO CVWF State RState
    1 4409 0x806a000 101 fd_server (0xfd ) - 1 BLOCK C [0x610]
    2 4409 0x8065000 0 main (0x0 ) - - RUNNING [0x209]
    
  • continue
  • quit

TDI source release

• get and install the generic TDI kernel (see the INSTALL file)
• get and install a TDI-aware Pthread implementation (patch if necessary)

   

  Pthreads implementation	TDI patch
  FSU Pthreads	not necessary
  MIT Pthreads	MIT patch
  Linuxthreads	Linuxthreads patch  (in progress )

• get Gdb-4.18, patch it with the gdb-4.18-TDI-04.patch, configure --enable-TDI, compile and install it
• see Installation Details for more information

If you want to learn more about the TDI Internals, for example in order to support another POSIX Threads implementation under TDI, check out the Developper's Pages.

You're welcome to make any suggestions and tell us your ideas. Please direct all TDI questions and bug reports to
 

known bugs:

• SunOS 4.1.x: SEGV at entry of thread function
• SunOS 4.1.x: SEGV for ptstack on main thread
• all: SEGV for repeated runs

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Last Modified: 1999-Jul-26

Authors: Daniel Schulz, Frank Mueller