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



James:

Kind of you to reply James.

Several months ago I queried the list for a hierarchical tree of functions associated with the execution of Xen and was told there was no such thing. 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. 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.

There are many brilliant code hackers that only need a starting point in the code and they are away. They build (compile and link) the code with a debugger, make notes, and change (add, delete, modify) on that basis until they get the required results from their testing. There is no question they are good at this as they generally live and breath every day doing this. But these sort in general may never have a comprehensive or top level down appreciation for the code or it's design. And that is the exact reason why such a graphic as explained above is needed. A "data dictionary" defining words and processes is also of great benefit. As soon as those brilliant hackers disappear into the land of opportunity and advancement no one understands the code or the overall integration of functionality because there is no such graphic. The Open and sometimes Free Software development would really benefit from this kind of documentation. Then , just maybe, people like me could jump in and really help. My experience in IT for many years (now retired) has taught me that there is nothing worse than jumping into a development group of these kind of hackers that know "their" way around the code "blind-folded" but cannot or will not pass that knowledge on to the "newbie" in the group in a documented way that facilitates rapid catchup to the other members in the group.

I'm not accusing anyone of anything in the Xen development group -- I am simply answering your question "Isn't that what LXR does - or have I missed the point?" You tell me as you obviously know more about LXR than I currently know. I have been away from software development now for many years and things have radically changed so I am still in the catchup mode and have to ask questions which are at times very elementary like my question about GRUB. I used to code my brains out in C and worked with other languages, Operating Systems, SQL and databases and that sort of thing. Now there is python matured, java this and java that, PHP in wide use, and so on. For another example, MySQL apparently has matured into a professional database technology where before I retired it was a laughing matter to use MySQL. So I have a lot of catching up to do and I'm on my way.

Thanks again for your email, posted in [Xen-devel] because it is a development issue.

Thanks, Ted


James Bulpin wrote:

On Fri, 1 Apr 2005, ted wrote:

:>Where would I obtain the perl code for this general hypertext
:>cross-referencing tool?

We use LXR version 0.3. This can still be found at http://lxr.linux.no/
(which is where your quote came from). There is a newer version available
that uses a database backend for the xref database. I think the "general
hypertext cross-referencing tool" refers to libraries within the LXR
package rather than a separate tool.

:>Would it not be possible to create a hierarchical tree structure of Xen
:>by parsing this display presented by the general hypertext
:>cross-referencing tool???

Isn't that what LXR does - or have I missed the point?

Regards,

James

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