Re: Strange stack trace on Windows

[Roland Schwingel <roland.schwingel@onevision.de>]

Hi...

Joel Brobecker wrote on 17.03.2009 16:08:35:
 > > Wouldn't it be possible to also adjust gdb's stepping code to work with
 > > your patch? Or (also not really nice, but maybe cleaner) to
 > > only use your patch for stack dumping. For stepping rely on the
 > > "other" (means current) frame code.
 >
 > Unfortunately, not. Everything is related: In order to determine whether
 > we stepped into a function during the "next", we do the equivalent of
 > a 2-frame backtrace.
 >
 > However, thinking about this a little more, perhaps there is a way out
 > for the "next" case: Try checking the PC against the start address
 > of the function. If the PC is at the start address of your function,
 > then the function prologue hasn't had time to adjust the stack in such
 > a way that we can't unwind from it, and thus the normal processing
 > should work.
That sounds interesting... :-)
Could you outline that a bit more? Where and how can I do that?
(I am digging in gdb's source only for a few days now).

 > > It is quite painful to use gdb on windows for quite a while now.
 > > Windows, whether one may like it or not, is a major platform
 > > and gdb should also operate well here. I am fighting for a long time
 > > with these problems now.
 >
 > As I hinted earlier, I think that this has to do with the fact that
 > you debug code that makes calls to functions that live inside DLLs.
 > This is a relatively specific condition...
Really so specific? I don't think so. Having dlls is quite common
on windows. The operating system itself is mostly a bunch of dlls. And if
one wants to use these functions he has to call them. As in my
example setbuf() from msvcrt.dll.
 
 > > Isn't there a general solution thinkable?  GDB is cool piece of
 > > software. For me it is "THE" debugger but this problem transforms more
 > > and more into killer problem here.
 >
 > Pedro answered exactly what I would have answered: The real proper
 > way to fix the problem is to teach GDB how to read the Windows "debug"
 > info. So far, no one has had enough interest in this project to see
 > it through.
Hmm.. Are so few people using gdb on windows? I think there should be
way more interest in getting gdb to deal right with MS debugging
format in order to get also debugging with frameless functions right.

Roland