Re: [PATCH] plugin patch

[Andrew Cagney <ac131313@redhat.com>]

> Plugins won't "know" the API that is used in newer versions of GDB, so
> they can't really decide whether they are or are not compatible with
> it. Only allowing plugins to be loaded with _exactly_ the same version 
> as the gdb they are loaded into works well (same way the linux kernel
> does).

That is correct.

Scott,

GDB's internals are undergoing massive change(1) and the various GDB 
interfaces reflect this.  A plug-in architecture only works when there 
is a stable published interface and GDB's current internal interfaces 
and mechanisms are about as far from `stable' and `published' as you can 
get :-/

Accepting this patch will create a situtation (actually very like the 
Linux kernel) where either:
- The plug-in developers play constant catch-up with GDB's evolving 
interfaces - every new release will require new plug-in.
- GDB's development stagnates because the plug-in developers depand the 
specification and support of an additional external interface (over and 
above MI(2)).

With regard to the modules that IBM and other vendors are planning on 
writing, can I encourage you to contribute them to the FSF?  That way, 
the entire Free Software Community would benefit (and this plug-in issue 
would be mute :-).

Andrew

(1) Don't believe me?  I'm currently commiting patches that eliminates 
registers[] from the core of GDB.  That interface, for too many many 
years, formed part of the foundation on which GDB was built.

(2) A long term MI objective is to define a set of interfaces that both 
MI and the CLI can use.  FernandoN made reference to this in responce to 
your original post.


> If the plugins are using a small number of functions only, you
> might want to consider using an API version number - whenever one of
> these functions changes, you increase the version number. This would
> allow plugins from various gdb versions (but with the same API
> version) to be used without the need of recompiling.
> 
> Jelmer
>