gdbserver on PowerPC Issues

gdbserver on PowerPC Issues

[Paul Mundt]

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Hi,

Currently when I try and debug an application via gdbserver running on a
PowerPC target (ep8260 in this case) I get the following:

$ powerpc-linux-gdb
GNU gdb 5.2.1
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you
are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for
details.
This GDB was configured as "--host=i686-linux --target=powerpc-linux".
(gdb) file hello
Reading symbols from hello...done.
(gdb) target remote 192.168.2.84:10002
Remote debugging using 192.168.2.84:10002
0x3000fa8c in ?? ()
warning: Unable to find dynamic linker breakpoint function.
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.
(gdb)

Now, looking through gnats, I see that someone had a similar problem and
this was logged as PR 236 -- to which there doesn't seem to be a fix.

Also looking through google, someone had suggested that this problem
might potentially be caused by having a stripped linker, and the linker
does indeed appear to be unstripped.

Any other suggestions?

Regards,

-- 
Paul Mundt
paul.mundt@timesys.com
TimeSys Corporation

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Re: gdbserver on PowerPC Issues

[Daniel Jacobowitz]

On Wed, Nov 20, 2002 at 12:21:57PM -0500, Paul Mundt wrote:
> Hi,
> 
> Currently when I try and debug an application via gdbserver running on a
> PowerPC target (ep8260 in this case) I get the following:
> 
> $ powerpc-linux-gdb
> GNU gdb 5.2.1
> Copyright 2002 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you
> are
> welcome to change it and/or distribute copies of it under certain
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for
> details.
> This GDB was configured as "--host=i686-linux --target=powerpc-linux".
> (gdb) file hello
> Reading symbols from hello...done.
> (gdb) target remote 192.168.2.84:10002
> Remote debugging using 192.168.2.84:10002
> 0x3000fa8c in ?? ()
> warning: Unable to find dynamic linker breakpoint function.
> GDB will be unable to debug shared library initializers
> and track explicitly loaded dynamic code.
> (gdb)
> 
> Now, looking through gnats, I see that someone had a similar problem and
> this was logged as PR 236 -- to which there doesn't seem to be a fix.
> 
> Also looking through google, someone had suggested that this problem
> might potentially be caused by having a stripped linker, and the linker
> does indeed appear to be unstripped.
> 
> Any other suggestions?

The problem is presumably that you haven't told GDB where to look for
the dynamic linker and shared libraries.  Try using 'set
solib-absolute-prefix' before you 'target remote'.

I suppose it might be worth adding to that message in order to make
this clearer...

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

Re: gdbserver on PowerPC Issues

[Paul Mundt]

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On Wed, 2002-11-20 at 13:39, Daniel Jacobowitz wrote:
> The problem is presumably that you haven't told GDB where to look for
> the dynamic linker and shared libraries.  Try using 'set
> solib-absolute-prefix' before you 'target remote'.
> 
Ah! This was indeed the problem. Though oddly enough, adjusting
solib-absolute-prefix didn't make the problem go away. I had to set it
to /dev/null and then set solib-search-patch to the proper directory
before the issue would fix itself.

There was some CRIS documentation hinting that that would only be
necessary if the end of the path wasn't /lib, but in this case it was.

Regards,

-- 
Paul Mundt <paul.mundt@timesys.com>
TimeSys Corporation

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Re: gdbserver on PowerPC Issues

[Daniel Jacobowitz]

On Wed, Nov 20, 2002 at 02:22:56PM -0500, Paul Mundt wrote:
> On Wed, 2002-11-20 at 13:39, Daniel Jacobowitz wrote:
> > The problem is presumably that you haven't told GDB where to look for
> > the dynamic linker and shared libraries.  Try using 'set
> > solib-absolute-prefix' before you 'target remote'.
> > 
> Ah! This was indeed the problem. Though oddly enough, adjusting
> solib-absolute-prefix didn't make the problem go away. I had to set it
> to /dev/null and then set solib-search-patch to the proper directory
> before the issue would fix itself.
> 
> There was some CRIS documentation hinting that that would only be
> necessary if the end of the path wasn't /lib, but in this case it was.

Mind setting solib-absolute-prefix and stracing GDB to see what it was
opening, then?  It really should work.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

Re: gdbserver on PowerPC Issues

[Paul Mundt]

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On Wed, 2002-11-20 at 14:21, Daniel Jacobowitz wrote:
> Mind setting solib-absolute-prefix and stracing GDB to see what it was
> opening, then?  It really should work.

My fault, I wasn't aware that solib-absolute-prefix appended /lib to the
path. As a result, it was looking in lib/lib, which caused ENOENT.

By handing it the path with the /lib trimmed, everything works fine.

Regards,

-- 
Paul Mundt <paul.mundt@timesys.com>
TimeSys Corporation

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Re: gdbserver on PowerPC Issues

[Andrew Cagney]

> On Wed, 2002-11-20 at 14:21, Daniel Jacobowitz wrote:
> 
>> Mind setting solib-absolute-prefix and stracing GDB to see what it was
>> opening, then?  It really should work.
> 
> 
> My fault, I wasn't aware that solib-absolute-prefix appended /lib to the
> path. As a result, it was looking in lib/lib, which caused ENOENT.

No, its a bug in the doco :-(  A better section on remote debugging is 
needed.

Andrew


> By handing it the path with the /lib trimmed, everything works fine.
> 
> Regards,
> 
> -- Paul Mundt <paul.mundt@timesys.com> TimeSys Corporation 

Re: gdbserver on PowerPC Issues

[Paul Koning]

>>>>> "Daniel" == Daniel Jacobowitz <drow@mvista.com> writes:

 Daniel> On Wed, Nov 20, 2002 at 02:22:56PM -0500, Paul Mundt wrote:
 >> On Wed, 2002-11-20 at 13:39, Daniel Jacobowitz wrote: > The
 >> problem is presumably that you haven't told GDB where to look for
 >> > the dynamic linker and shared libraries.  Try using 'set >
 >> solib-absolute-prefix' before you 'target remote'.
 >> > 
 >> Ah! This was indeed the problem. Though oddly enough, adjusting
 >> solib-absolute-prefix didn't make the problem go away. I had to
 >> set it to /dev/null and then set solib-search-patch to the proper
 >> directory before the issue would fix itself.
 >> 
 >> There was some CRIS documentation hinting that that would only be
 >> necessary if the end of the path wasn't /lib, but in this case it
 >> was.

 Daniel> Mind setting solib-absolute-prefix and stracing GDB to see
 Daniel> what it was opening, then?  It really should work.

Depends on whether the library names are given in the image with a
leading slash or not.  If yes, then the absolute prefix setting
matters; if not, the search path.

	 paul

Re: gdbserver on PowerPC Issues

[Daniel Jacobowitz]

On Wed, Nov 20, 2002 at 02:29:54PM -0500, Paul Koning wrote:
> >>>>> "Daniel" == Daniel Jacobowitz <drow@mvista.com> writes:
> 
>  Daniel> On Wed, Nov 20, 2002 at 02:22:56PM -0500, Paul Mundt wrote:
>  >> On Wed, 2002-11-20 at 13:39, Daniel Jacobowitz wrote: > The
>  >> problem is presumably that you haven't told GDB where to look for
>  >> > the dynamic linker and shared libraries.  Try using 'set >
>  >> solib-absolute-prefix' before you 'target remote'.
>  >> > 
>  >> Ah! This was indeed the problem. Though oddly enough, adjusting
>  >> solib-absolute-prefix didn't make the problem go away. I had to
>  >> set it to /dev/null and then set solib-search-patch to the proper
>  >> directory before the issue would fix itself.
>  >> 
>  >> There was some CRIS documentation hinting that that would only be
>  >> necessary if the end of the path wasn't /lib, but in this case it
>  >> was.
> 
>  Daniel> Mind setting solib-absolute-prefix and stracing GDB to see
>  Daniel> what it was opening, then?  It really should work.
> 
> Depends on whether the library names are given in the image with a
> leading slash or not.  If yes, then the absolute prefix setting
> matters; if not, the search path.

Right, but Paul's using a Linux target; both of the Linux dynamic
loaders I'm familiar with set full paths in the linker map. 
Fortunately, problem solved now!

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer