Monday, July 23, 2012

Talk On Enix Operating System

Today in our research seminar, I did a presentation on a research paper. The paper I selected was "Enix: A Lightweight Dynamic Operating System for Tightly Constrained Wireless Sensor Platforms" [link] which is published in year 2010 at ACM SenSys conference. Since Operating Systems is one of my favourite courses I learnt in university, I wanted to present an OS related paper in the research seminar. Additionally, since this Enix OS is intended for wireless sensor network platforms it is related to my final year research too. Therefore I picked this paper.

Enix is currently implemented to run on an experimental platform called EcoSpire nodes. However according to the authors it can be easily ported to other platforms too. Among the features provided in Enix, the most significant work they contribute according my point of view is the virtual memory implementation.

Virtual memory functionality in Enix

Enix supports virtual code memory with the assistance of the compiler. Library functions are compiled in to position independent code (PIC) segments and stored in the Micro-SD card. All the user application calls to these functions are directed to a special run-time loader in the kernel space. This loader finds the required functions in the Micro-SD card and load it to an empty space in memory. Since these functions are compiled in position independent manner, no run-time relocations required. Copied functions can just start running from wherever they loaded. This is how the overhead of run-time relocation is removed in Enix with the assistance of compiler. However I think position independent codes introduce some computational overhead than normal executable codes. In  addition to the virtual memory, Enix provides an it's own file system called EcoFS. 

After my presentation we had a nice discussion where we talked about different aspects in particular Enix and in general about WSN operating systems. Even though I was a little bit nervous before the presentation, I think I could do it without any issue. :) I'm feeling so much happy about it.

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