Insight 6.0 and Dlls

Insight 6.0 and Dlls

[Heiko Gerdau]

Hi,

I'm using insight 6.0 and try to debug a programm that loads dlls (I'm on 
SuSE Linux 8.2).

The problem: After running the programm and breaking in main insight should 
have access to the dll symbols and sources but does not show them in the 
dropdown list of available source files.

If I load the source manually using the file menu insight does not 
recognize it as part of the application (no dashes at the beginnings of 
lines).

It works though if I use the console and set a breakpoint like 
"foo.cpp:234". After hitting the source line insight displays the source.

Is this a bug or what should I do to set a dll breakpoint using the gui and 
not the console?

Greetings
Heiko 

Re: Insight 6.0 and Dlls

[Keith Seitz]

On Tue, 2004-01-06 at 06:05, Heiko Gerdau wrote:

> The problem: After running the programm and breaking in main insight should 
> have access to the dll symbols and sources but does not show them in the 
> dropdown list of available source files.

I think that the real problem is that Insight doesn't get any
library-loaded events. Nonetheless, I thought that I'd worked around
this problem by restuffing the source window's combo boxes whenever we
read symbols.

I can see in src/gdb/gdbtk/library/interface.tcl that the procedure
gdbtk_tcl_post_add_symbol does, indeed, attempt to refill the combo
boxes. Is this not being called when the shared library is loaded (You
can put a "puts" in there or a debug statement that will show up in the
debug window)?

Keith

Re: Insight 6.0 and Dlls

[Heiko Gerdau]

On Wednesday 21 January 2004 15:56, Keith Seitz wrote:
> On Tue, 2004-01-06 at 06:05, Heiko Gerdau wrote:
> > The problem: After running the programm and breaking in main insight
> > should have access to the dll symbols and sources but does not show
> > them in the dropdown list of available source files.
>
> I think that the real problem is that Insight doesn't get any
> library-loaded events. Nonetheless, I thought that I'd worked around
> this problem by restuffing the source window's combo boxes whenever we
> read symbols.
>
> I can see in src/gdb/gdbtk/library/interface.tcl that the procedure
> gdbtk_tcl_post_add_symbol does, indeed, attempt to refill the combo
> boxes. Is this not being called when the shared library is loaded (You
> can put a "puts" in there or a debug statement that will show up in the
> debug window)?

gdbtk_tcl_post_add_symbol seems to be never called. At least I can't see 
any output from my puts and debug statements at any time.

Just to make sure: I have also put some similar debug statements into the 
function fillNameCB and I see those messages only from the combobox 
filling at startup.

Greetings
Heiko

Re: Insight 6.0 and Dlls

[Heiko Gerdau]

Hi,

is there anybody who can reproduce this. Or does it happen just with my 
configuration?

Thanks
Heiko

On Saturday 24 January 2004 01:26, Heiko Gerdau wrote:
> On Wednesday 21 January 2004 15:56, Keith Seitz wrote:
> > On Tue, 2004-01-06 at 06:05, Heiko Gerdau wrote:
> > > The problem: After running the programm and breaking in main insight
> > > should have access to the dll symbols and sources but does not show
> > > them in the dropdown list of available source files.
> >
> > I think that the real problem is that Insight doesn't get any
> > library-loaded events. Nonetheless, I thought that I'd worked around
> > this problem by restuffing the source window's combo boxes whenever we
> > read symbols.
> >
> > I can see in src/gdb/gdbtk/library/interface.tcl that the procedure
> > gdbtk_tcl_post_add_symbol does, indeed, attempt to refill the combo
> > boxes. Is this not being called when the shared library is loaded (You
> > can put a "puts" in there or a debug statement that will show up in
> > the debug window)?
>
> gdbtk_tcl_post_add_symbol seems to be never called. At least I can't see
> any output from my puts and debug statements at any time.
>
> Just to make sure: I have also put some similar debug statements into
> the function fillNameCB and I see those messages only from the combobox
> filling at startup.
>
> Greetings
> Heiko

Re: Insight 6.0 and Dlls

[Keith Seitz]

On Thu, 2004-02-05 at 07:41, Heiko Gerdau wrote:
> Hi,
> 
> is there anybody who can reproduce this. Or does it happen just with my 
> configuration?
> 

Ok, I don't know why, but I've spent a few minutes browsing the sources
to see what might be going on.

The problem lies within gdb -- not insight. Of course, like many things,
the problem is really only visible inside a GUI. :-(

Most of the action is in src/gdb/win32-nat.c. This file contains all the
native code for cygwin and it contains the main target event loop for
windows hosts. The function child_wait is this event loop.

It loops indefinitely calling get_child_debug_event. If you look at this
function, you'll see that one of the events that it knows about is
LOAD_DLL_DEBUG_EVENT. This informs the "tdep" code (the "t"arget
"dep"endent code -- not core gdb) that a DLL has been loaded.

This returns that status TARGET_WAITKIND_LOADED to core gdb. In turn, if
you look where this event is handled in infrun.c's
handle_inferior_event, you'll see that it calls SOLIB_ADD to notify the
rest of gdb that a shared library/DLL was loaded. For cygwin,
src/gdb/config/i386/tm-cygwin.h defines SOLIB_ADD as "child_solib_add".
Eventually, this calls symbol_file_add in src/gdb/symfile.c.

Look closely at the call to SOLIB_ADD:

	SOLIB_ADD (NULL, 0, &current_target, auto_solib_add);

The second parameter here, "0" is the "from_tty" argument. Sadly, this
is problematic.

If you look at symbol_file_add now, we see that the
pre/post_add_symbol_hooks are ONLY called if from_tty != 0 or "info
verbose" has been set.

Now, I cannot tell you that setting "info verbose" in gdb proper will
not interfere with insight, but I do think that there is a fundamental
problem with the hooks not being called in this case.

Should from_tty be non-zero? I don't know.
Should the hooks be called no matter what? I don't remember. I have
vague recollections that there was a reason for the from_tty thing. :-(

I've run through the CVS history, and I see that SOLIB_ADD has always
had from_tty set to 0. Yet I remember clearly that this used to work.
From the looks of it, it would appear that this shouldn't work on unix,
either.

Well, that's all I have right now. You migt as well try setting info
verbose and seeing if that helps works around it for now.

Keith

Re: Insight 6.0 and Dlls

[Heiko Gerdau]

On Thursday 05 February 2004 19:24, Keith Seitz wrote:
> On Thu, 2004-02-05 at 07:41, Heiko Gerdau wrote:
> If you look at symbol_file_add now, we see that the
> pre/post_add_symbol_hooks are ONLY called if from_tty != 0 or "info
> verbose" has been set.
>
> Now, I cannot tell you that setting "info verbose" in gdb proper will
> not interfere with insight, but I do think that there is a fundamental
> problem with the hooks not being called in this case.
>
> Should from_tty be non-zero? I don't know.
> Should the hooks be called no matter what? I don't remember. I have
> vague recollections that there was a reason for the from_tty thing. :-(
>
> I've run through the CVS history, and I see that SOLIB_ADD has always
> had from_tty set to 0. Yet I remember clearly that this used to work.
> From the looks of it, it would appear that this shouldn't work on unix,
> either.
>
> Well, that's all I have right now. You migt as well try setting info
> verbose and seeing if that helps works around it for now.

Thanks for pointing this out. If I do the two changes below in function 
"symbol_file_add_with_addrs_or_offsets" in symfile.c the insight combobox 
is blinking heavily on startup but gets all the source files from all the 
libraries with debugginjg information.

I commented out:
lines 887 and 963 in symfile.c each containing
/*  if (from_tty || info_verbose) */

Thanks
Heiko