New features for GDB under Windows

New features for GDB under Windows

[Martin Rosenau]

Hello.

I'm new to the GDB project so I do not know if this is the correct place
to post this message.

5 months ago I wrote some enhancements for GDB under Windows.
Unfortunately I did not patch GDB 7.x but only 5.2.1 because this was
the latest version available for the Mingw system under Windows.

I added the following functionality that was only available under Unix
before:
- Remote debugging using TCP/IP
- Remote debugging using pipes (other program's stdin/stdout)

And the new feature:
- Remote debugging using special DLLs (this is faster than TCP/IP or
pipes and allows you to add new hardware targets - like JTAG adapters -
without re-compiling the entire GDB)

I wonder if these features are of interest and if yes how I can post it
to the GDB project.

Thanks for your answer.

Martin

Re: New features for GDB under Windows

[asmwarrior]

  On 3:59, Martin Rosenau wrote:
> Hello.
>
> I'm new to the GDB project so I do not know if this is the correct place
> to post this message.
>
> 5 months ago I wrote some enhancements for GDB under Windows.
> Unfortunately I did not patch GDB 7.x but only 5.2.1 because this was
> the latest version available for the Mingw system under Windows.

As far as I know, there is a gdb mingw download page, see here:
https://sourceforge.net/downloads/mingw/MinGW/BaseSystem/GDB/
Five monthes ago, it should be at least gdb 6.8.3. or gdb 7.x.

> I added the following functionality that was only available under Unix
> before:
> - Remote debugging using TCP/IP
> - Remote debugging using pipes (other program's stdin/stdout)
>
> And the new feature:
> - Remote debugging using special DLLs (this is faster than TCP/IP or
> pipes and allows you to add new hardware targets - like JTAG adapters -
> without re-compiling the entire GDB)
>
> I wonder if these features are of interest and if yes how I can post it
> to the GDB project.

These are nice features, and you can follow the direction here:
http://www.gnu.org/software/gdb/contribute/


asmwarrior (ollydbg from codeblocks' forum)

Re: New features for GDB under Windows

[Daniel Jacobowitz]

On Sun, Jul 18, 2010 at 12:04:52PM +0800, asmwarrior wrote:
> >I added the following functionality that was only available under Unix
> >before:
> >- Remote debugging using TCP/IP
> >- Remote debugging using pipes (other program's stdin/stdout)

Both of these are already included in current versions of Windows
GDB.

> >And the new feature:
> >- Remote debugging using special DLLs (this is faster than TCP/IP or
> >pipes and allows you to add new hardware targets - like JTAG adapters -
> >without re-compiling the entire GDB)

I don't know if this is a desired feature.  It runs into maintenance
and GPL compliance problems.

-- 
Daniel Jacobowitz
CodeSourcery

Re: New features for GDB under Windows

[Martin Rosenau]

Daniel Jacobowitz wrote:
> On Sun, Jul 18, 2010 at 12:04:52PM +0800, asmwarrior wrote:
>>> I added the following functionality that was only available under Unix
>>> before:
>>> - Remote debugging using TCP/IP
>>> - Remote debugging using pipes (other program's stdin/stdout)
> 
> Both of these are already included in current versions of Windows
> GDB.
> 
Thanks for that information.
I had a look at the WebCVS and noticed that TCP now really works with
Windows.

However I thinks pipes will only work with Cygwin (Unix simulation on
Windows), not with native Windows (required by Mingw etc.). I still
could apply my patch to the current version of ser-pipe.c, if it is desired.

I also saw that the "remote-array.c" file has been removed; this file
caused a problem trying to use the "monitor" command together with
serial/pipe/TCP targets.

>>> And the new feature:
>>> - Remote debugging using special DLLs (this is faster than TCP/IP or
>>> pipes and allows you to add new hardware targets - like JTAG adapters -
>>> without re-compiling the entire GDB)
> 
> I don't know if this is a desired feature.  It runs into maintenance
> and GPL compliance problems.
> 
The GPL compliance problems are an old problem running GPL programs
under Windows. In some Internet forum I read the discussion if it is
allowed to run GPL programs under Windows at all (it is (nearly)
impossible to run any program under Windows without using Windows'
closed-source DLLs!)
Unfortunately there was no final conclusion about this problem.

If the license problems should be critical some text in the GDB manual
could state something like "The plug-in DLLs used must be under GPL or
LGPL license, otherwise you may violate the license terms of GDB".

What I do not understand is the term "maintenance problems". Do you think
- about compatibility problems (a DLL for 7.x could not run under 8.x)
- or about the "who is responsible" problem (provider of the DLL says:
"bug in GDB", GDB team says: "bug in DLL")
- or are you afraid that there are too many targets in GDB
- or do you think about other problems?

Thanks for your answer.

Martin

Re: New features for GDB under Windows

[Daniel Jacobowitz]

On Mon, Jul 19, 2010 at 08:24:52AM +0200, Martin Rosenau wrote:
> However I thinks pipes will only work with Cygwin (Unix simulation on
> Windows), not with native Windows (required by Mingw etc.). I still
> could apply my patch to the current version of ser-pipe.c, if it is desired.

I use pipes with a mingw32 every day, and so do our customers.  So, I
know it works.  But if you know of a remaining problem, then we could
discuss your patch.

> >>> And the new feature:
> >>> - Remote debugging using special DLLs (this is faster than TCP/IP or
> >>> pipes and allows you to add new hardware targets - like JTAG adapters -
> >>> without re-compiling the entire GDB)
> > 
> > I don't know if this is a desired feature.  It runs into maintenance
> > and GPL compliance problems.
> > 
> The GPL compliance problems are an old problem running GPL programs
> under Windows. In some Internet forum I read the discussion if it is
> allowed to run GPL programs under Windows at all (it is (nearly)
> impossible to run any program under Windows without using Windows'
> closed-source DLLs!)
> Unfortunately there was no final conclusion about this problem.

That's a completely different problem.  There's language in the GPL to
describe exactly what is going on in that situation; it's called the
"system library exception", IIRC.

> What I do not understand is the term "maintenance problems". Do you think
> - about compatibility problems (a DLL for 7.x could not run under 8.x)

This is the primary issue.  If we allow plugins, we need to define,
validate, maintain, and preserve an interface for them.  We don't want
to do that.  At least, I don't.

I've never seen a GDB that used external DLLs for target access and
didn't violate our understanding of the GPL (and I've seen at least
two that I can recall).

-- 
Daniel Jacobowitz
CodeSourcery