Re: [Xen-devel] lxr.xensource.com-lxr

[James Bulpin <James.Bulpin@xxxxxxxxxxxx>]

On Fri, 1 Apr 2005, Ted Hilts wrote:

:>Cross Referencing is nice but is not a hierarchical tree like display of
:> the dependent order of execution of all functions.  Essentially there
:>is the "main" module which calls subordinate modules which in turn call
:>their subordinante modules and the entire scenario can be graphically
:>displayed  in connecting lines to box like structures that identify the
:>function called and it's purpose and data passed back and forth if any.

Ah, a graphical representation of the call graph?

:> The graphic is most often layered with the top layer being the main
:>routine, the next layer being the routines called by the main routine,
:>the next layer down  has the routines called by the second layer and so
:>on.  This graphic gives a good idea of the software architecturee and is
:>invaluable if there are parallel streams of execution.  Often, software
:>development builds stubs for unwritten code and works from the top down
:>according to a design plan in the graphical form I have explained.

I suspect that for such a graphic to be truly useful it would have to be
(at least partially) manually created. The event driven nature of an
system software is such that the call graph is not a nice, clean tree of
multiple separate layers. An additional problem is that static analysis of
the code would not give the full call graph because of things like
dynamically registered handlers, callbacks etc..

So I guess there are two possible documents that fit what you are looking
for:

 - a high level architecture overview - we generally rely on the papers
   written about Xen for this
 - a low level call graph representation, automatically generated, i.e.
   LXR++

I'm happy to take suggestions for tools for the latter which we may be
able to host in a similar way to the existing LXR.

:>I am simply answering your question "Isn't that what LXR does - or have
:>I missed the point?"

Thanks. I hadn't quite unerstood what you meant "tree" - I assumed
directory tree.

James

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