Book Review: Linux Unwired

by Jim Thompson

Publisher: O'Reilly & Associates

ISBN: 0-596-00583-0

Price: $24.95 US

Linux Unwired covers using 802.11, Bluetooth, IrDA, various cellular data standards and, finally, GPS. Although the subject matter is interesting and topical for owners of Linux notebooks, the books authors, editors and reviewers have left the audience under rewarded for both the price of and the time spent reading this book.

Over half of the book covers using 802.11 with Linux, and this section contains quite a few flaws. In the first 50 pages, I could find only three pages without an error or omission, and some pages are somewhat more marred. When the subject matter is Linux-specific, the book is near perfection, but the book's authors stumble when filling in the background material. Perhaps an example is in order. On page 21, the book's authors claim: “Atheros is unique in that its chipsets are not based on the Intersil Prism II reference design....Atheros has since introduced dual-mode 802.11a/b radios with its ar5211 chipset and tri-mode a/b/g radios using their ar5212 chipset.”

First, no vendor but Intersil based its chipset(s) on the Prism II design. For example, Lucent/Agere manufactured its own chipsets for both the 802.11b and 802.11a/b/g standards. As a rule, chipset vendors typically do not license the designs (IP) for their chipsets. Moreover, the reference design is for a Wi-Fi card or perhaps an AP, not a chipset.

The second error is the Atheros AR5211 and AR5212 are chips, not chipsets. Each requires one or two Radio On a Chip (ROC) partner chip(s) to be connected to the AR5211 or AR5212 in order to pass form a solution:

  • AR5211 + AR5111 = 802.11a (only)

  • AR5211 + AR5111 + AR2111 = 802.11a/b/g

  • AR5212 + AR2112 = 802.11g/802.11b

See, for example, www.atheros.com/pt/ar5001X+.html and www.atheros.com/pt/AR5002XBulletin.htm.

Some facts presented in Linux Unwired would be patently false were they not preceded with the oft repeated, “at the time of writing”. Only a year after the book's claims on WPA were written, both the hostap and madwifi drivers support the authenticator and supplicant modes of WPA. In fact, the Linux drivers for Intel's Centrino and 54Mbps Intersil cards now offer close to full WPA supplicant support. Perhaps this is testament to the rapid development pace of FLOSS, nevertheless, this section quickly is becoming stale.

The other four subjects are covered with fewer errors. The Bluetooth and cellular data sections are rewarding, while the GPS and IrDA sections seem slightly out of place. IrDA is an established technology with a market presence rapidly being consumed by Bluetooth. Although interesting, GPS hardly could be described as a networking protocol. The cognitive pileup that results from reading a book composed of 250 pages discussing Linux and untethered communication technologies and ending with a 30-page chapter on a location-finding technology causes confusion, to say the least

My hope for Linux Unwired is that its success warrants a revision. Technical book often are used as maps through uncharted waters, and they should not lead inexperienced readers astray in their quest for knowledge.

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