Readers sound off.

Letters

No Accounts for the Penguins?

On a recent trip to the Camden Aquarium in Camden, New Jersey, I found that the penguins were attracted to my Linux hat. My girls loved the penguins, and I plan on raising them on Linux desktops (the girls that is).




Shane M. Parker

BSD, Please

May I suggest including other open-source UNIX-like operating systems? I have just installed OpenBSD for a project at work. Although it would have been easier with Linux, if the boss says BSD then it is BSD. I must admit that it was a pain; however, after going through the process for the right application environment, OpenBSD would be a good choice. In my opinion, Lintel is no better than Wintel. I would urge you to consider articles on ports, the BSD solution to software distribution. Two choices are better than one but not much better.


raymond a jacob jr

Check out www.lnx-bbc.org/garticle.html for an updated version of the Embedded Linux Journal article on GAR, a ports-like software build system. —Ed.

LJ Web Site—Too Political?

The article I received via e-mail titled “Hot Air” (linuxjournal.com/article/7493) was a huge disappointment to me. Now, I am not a conservative. I am a liberal, but not the socialist flavor represented by Kerry and Kennedy. This, however, is all beside the point. Using this technical forum to promote these views is the kind of thing that frankly makes me want to cancel my subscription. Having said that, I'm willing to give LJ one more chance, but I will be paying closer attention to what comes in my e-mail. When I want politics, I know where to go to get it, and I won't support your magazine with my dollars so they can be spent promoting political agendas.


Jake Fear

Doc Searls replies: if Air America were a right-wing network in the same position, I would have covered it the same way. Was the whole thing a stretch as a Linux subject? Sure. But I think it would help broadcasters of all sorts to take advantage of Linux, the Net and technologists who understand both. That's what I was trying to get across.

We've been writing about the intersection of Linux, the Net and radio for years, by the way. The Web site has much more room for material, and much more leeway around subject matter, than the magazine.

I'm sorry the piece disappointed you, and that you saw it promoting a political agenda. For what it's worth, I'm a registered independent. In recent elections I've mostly voted Libertarian. If there's an ax I try not to grind, that's the one.

Thanks for the Recommendation

Wow! After reading Marcel Gagné's article on SuperKaramba [LJ, May 2004], I took just a few minutes and configured it for my system. Hats off to all the SuperKaramba and theme authors and to Marcel for bringing this to your readers' attention. Thanks for the great magazine and the great articles.


Robert Fields

Everybody SPF Now!

Why would your publication be so pro-SPF without publishing an SPF record for your own domain?


Nicholas Marsh

Try it now, with host -t txt linuxjournal.com. More SPF info at spf.pobox.com. —Ed.

Shielded CPUs vs. RTLinux/RTAI

I enjoyed the article entitled “Shielded CPUs: Real-Time Performance in Standard Linux” in the May 2004 issue of your magazine. I have two brief comments about this article that should be perceived as constructive criticism.

1) Steve Brosky could have been even more informative in his performance numbers had he also compared the interrupt response times of his shielded CPUs technique to the more conventional RTLinux/RTAI (which he himself acknowledges as being a very good standard by which to judge a real-time solution). The advantage of providing actual numbers that compare his system to RTLinux/RTAI is that it would have helped people to decide more quickly which RTOS is right for them.

Specifically, RTLinux and RTAI have better performance numbers, with latency and jitter measured in the 10s of microseconds, not 100s, as was demonstrated using shielded CPUs. For some applications the shielded CPUs technique is sufficient, while for others it is not. Having had sets of numbers representing RTLinux/RTAI would have helped people to decide more quickly which real-time approach is right for them.

2) The article should have spent more time discussing the potential pitfalls inherent to the shielded CPUs technique. Specifically, CPU shielding still suffers from priority inversion problems inherent in any system that shares resources with non-real-time components. In order for CPU shielding to guarantee hard real-time performance, one must be careful to write programs that do not access any potentially blocking operations in the Linux kernel.

More specifically, any swapping of memory to disk in the shielded process throws real-time performance out the window. One has to do things like lock all process memory to RAM, for example, mlockall(), as well as be careful not to access any device drivers that may run on non-shielded CPUs or that may sleep. This must be done in order to avoid priority inversion with the normal, non-real-time, Linux system.

Overall, a good article, but it could have been even more informative, in my opinion, had the two points above been addressed.


Calin A. Culianu

Steve Brosky replies: there are a lot of things that could have gone into the article—but with limited space you pick and choose what to include.

Photo of the Month: More Fashion Ideas

Robert Henry's Halloween picture in the May 2004 issue of Linux Journal prompts me to send you this photo of my two children taken two years ago.




Dr Stuart DeGraaf

Photo of the Month gets you a one-year extension for your subscription. Anyone have a hobby other than sewing? Photos to ljeditor@linuxjournal.com. —Ed.

Bank Answer One: Monoculture Is Risk

I just read [William Mitchell's] letter to the editor in the May 2004 issue about Microsoft IE-only bank Web sites. As he mentioned that his bank did this, a letter to the chairman of the board and the board of directors might do the trick. I suspect if one points out that mandating usage of the least secure Web browser is not only an annoyance to those who use more secure ones, but that insisting on this puts the bank at risk for more theft, this may change.


Anonymous

Answer Two: Moo-ve to Another Bank

What I would do in Mr Mitchell's case is inform my bank that I am the customer. They exist to service me, and not like a bull services a cow, either. If they choose not to do that, then I will simply find a bank that will.


John McKown

Answer Three: Fake It

I've been using User Agent Switcher for Mozilla and Firefox to get to sites that claim to be IE/Netscape-only friendly. It's been working fine. You can check it out here: www.chrispederick.com/work/firefox/useragentswitcher.

I'd e-mail William Mitchell but you don't post e-mails in the Letters section, for obvious reasons! Maybe you could pass this on to him.


Sam Mingolelli

Another Satisfied Reader

I just wanted to let you know how much we all look forward to reading your magazine each month. Keep on doing what you're doing.




Dan

sudo adduser bhm

We've run enough photos of readers' and contributors' children that it's time for one from an editor. Here's a photo of my son Bilal at age zero days.




Don Marti

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