Re: gdb and the vxworks target

[jtc at redback dot com (J.T. Conklin)]

>>>>> "Till" == Till Straumann <strauman@SLAC.Stanford.EDU> writes:
Till> As of Version 5.4, WindRiver has more or less silently removed
Till> support for the RDB protocol. This means that the gdb target
Till> `vxworks' no longer works with VxWorks versions later than 5.3

Till> However, there is another server on the vxWorks target talking a
Till> different protocol, WDB, which at least is quite well documented.

It's OK, but at least in the copy of the WDB spec I have there are
some holes, such as in what set and at what offset each register is
located for the get/fetch register commands.  I wasn't able to find
the WTX or WDB specs in the Tornado II documentation --- I got the
impression that they (WRS) wants to hide such details under their
proprietary libraries.  That makes it a bit difficult for third party,
open source, multi-platform tools like GDB.

We're using a WDB back end I hacked from Wind River's vxgdb sources
remote-wtx.c module.  I've been meaning to re-write those bits so I
could contribute it for the last year or so.  Unfortunately, it's a
fairly low on my priority list.

If your code isn't similarly encumbered, and you're able to contribute
it, it's probably a faster route to supplying WDB support to GDB users.

Till> I added support for WDB to `remote-vx.c' which means that gdb
Till> can again talk to vxworks :-) The CPU dependent parts (a very
Till> tiny piece of code) are currently only implemented for the
Till> powerpc (I could easily add m68k, if there's any need).

Did you maintain support for RDB in the process?  While WRS has
dropped support for RDB, there may be vxworks users in the field that
still use it.  We should continue to support it if at all possible.

If you kept RDB support, how much code for RDB and WDB are shared in
remote-vx.c?  In our sources, remote-wdb is completely separate.

Till> Because WDB lacks some functionality that RDB had provided (on
Till> the other hand, WDB adds new features), I also wrote a small
Till> server which can be started on the target. This server
Till> implements a subset of the RDB protocol, essentially the parts
Till> which are necessary to remotely load files and lookup modules.

When you talk about a "small server that can be started on the target",
you're talking about something that runs on the vxWorks system, right?
Another engineer here hacked code into my remote-wdb.c to support 
remotely loading files, but it works entirely with WDB.  Can you
please explain more?

We also have a WDB multiplexor so that multiple GDBs, each connected
to a single vxWorks task, can debug a system.

        --jtc

-- 
J.T. Conklin
RedBack Networks