Messages in this thread | | | Date | Fri, 24 May 2002 19:05:13 -0400 | From | Karim Yaghmour <> | Subject | Re: patent on O_ATOMICLOOKUP [Re: [PATCH] loopable tmpfs (2.4.17)] |
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Thanks for taking the time to look at this Linus. I understand what you are saying, but I think that there is a large part of the history of the rtlinux patent that has not been properly communicated to the kernel developers. I will try my best to explain this in the following, but feel free to ask questions if things need clarifications. There is only so much I can put in one mail.
When the patent was first noticed by Jerry Epplin in early 2000, he posted a question about it on the rtlinux mailing list. Here is Victor's reply at the time: http://lwn.net/2000/0210/a/vy-patent.html The message clearly says: "The main purpose of the patent was defensive ..."
So the real-time Linux community waited for what was to follow.
Next came the first version of the patent license. That version violated the GPL itself, requiring you to register all the users of the software with FSMLabs. Plus, it had the following "APPROVED USE" section: In addition to the other terms and conditions of this License, use of the Patented Process is permitted, without fee or royalty, when used:
A. By software licensed under the GPL; or
B. By software that executes within an Open RTLinux Execution Environment - whether that software is licensed under the GPL or not.
Basically, Victor was saying that anyone wanting to write a real-time application must either license it under GPL or use FSMLabs' Open RTLinux Execution Environment, a version of RTLinux distributed by FSMLabs.
Many in the real-time Linux community were, evidently, displeased with this turn of events and tried to obtain clarifications from Victor. To this day, however, the real-time Linux community is still waiting for the answers to very basic questions such as: "Does anyone developping a non-GPL application for RTAI (the other real-time Linux extension) have to pay licensing fees to FSMLabs?"
This matter remained unchanged until the FSF came out later and declared publicly that the patent was violating the GPL. At that time, Eben Moglen came out and publicly explained the implications of the patent and the "corrected" patent license. Here is Eben's explanation: http://www.aero.polimi.it/~rtai/documentation/articles/moglen.html
Basically, this calmed things down and the RTAI development team, including myself, tried to comply with Eben's recommendations.
All would have been fine if things had ended there, but Victor then came out and threw more uncertainty about the matter: http://linuxdevices.com/articles/AT6164867514.html
Just when Eben Moglen was saying that real-time applications were not subject to the patent, Victor Yodaiken came out and said: "If you want to make, use, sell, distribute, import, etc. non-GPL software -- regardless of whether such software is labeled as an "application," "module," or anything else -- please make sure you have obtained competent legal advice regarding whether your software and its use is an approved use under the Open RTLinux Patent License or whether a license under the RTLinux patent must be secured to authorize your software and its use."
This was certainly not helpful. When I asked Victor why he did this, he said > I can't offer legal advice. My understanding is that these things can be > quite complex.
I could have understood that this was indeed genuine, but here we have Eben Moglen, a respected lawyer, publicly clarfying a situation and instead of backing his position or keeping simply silent, Victor comes out and casts a doubt on the very clarifications made by Eben.
The story goes on and the real-time Linux community is still in limbo. At this stage, my understanding is that the FSF is very upset with Victor's latest comments. But the FSF's point of view or its dealings with Victor's patent are only a partial picture of this story.
In reality, the patent is but the tip of the iceberg.
To get the real picture, you must understand what has happened to the various real-time projects in existence: RTAI and RTLinux. Today, RTAI has clearly taken the lead as the primary real-time addition to Linux. But it only got there because all the developers who work on it today were, at one point or another, very interested in making contributions to RTLinux. In every instance, they were turned down or dismissed by Victor. And in most instances, those who were turned down went to work on RTAI.
And there is a very logical reason for this. FSMLabs dual-licenses RTLinux in closed-source form to many of its clients. This involves that it be the owner of all the code within RTLinux. And indeed, if you take a look at the core files making up RTLinux, they all belong to FSMLabs and FSMLabs alone. There is nothing wrong with this per se. But it does affect the development policy of RTLinux since no outside contributions are ever included in RTLinux's codebase.
At most, there is "contributors" file with some names, but no copyrights in the files. Which begs for a very fundamental question: Has no one ever made a contribution to RTLinux? If someone has, then why are there no names in those file headers except FSMLabs'?
At this point in time, all the bleeding-edge development being done in RTLinux is not available in GPL and must be purchased for a fee.
This isn't really a problem, since RTAI has now surpassed RTLinux in terms of capabilities, ports and support. The problem, however, is that the rtlinux patent is being used to wage an FUD campaign against RTAI.
Hence, someone who currently wants to do real-time in Linux digs a little and finds RTLinux and RTAI. He then tries to get the latest and greatest in RTLinux and realizes that the GPL RTLinux is actually a bait-and-switch. So he takes a closer look at RTAI, but as soon as he does this he sees all these warnings given out by Victor about RTAI and decides to drop Linux altogether and use another OS.
This isn't an imaginary scenario. This has happened time and again with many very big name users. I can provide you with email addresses of people you ask about this.
To sum up, anyone today wanting to do real-time development with Linux faces a barrage of uncertainty. Even if he uses the now GPL RTAI, he doesn't know whether he needs to purchase licenses for his non-GPL applications.
Notice that the argument that the rt tasks running on RTAI must also be GPL because RTAI is GPL doesn't hold because RTAI allows normal Linux processes to become full hard-real-time tasks. This is done through a single call to the RTAI layer rt_make_hard_real_time(). When this function is called, RTAI steals the task from the Linux scheduler and schedules it himself. Hence, the entire task is in user-space.
And as the copyright notice in the kernel sources says, user applications are not subject to the GPL. You added this yourself because you felt that application developers should not be subject to the GPL. The real-time Linux community only expects the same. We don't want a non-GPL real-time executive or a non-GPL OS. All we want is the right to develop applications using our licenses as others are for Linux. We have tried to obtain this through discussion and through enforcement of the GPL. Every time, we faced FUD and unanswered questions. The only venue left today is a total dismissal of the patent.
One last thing: Clearly, if non-GPL applications were not allowed with Linux, we wouldn't be talking today. The same holds for non-GPL RT apps.
I hope this has provided some insight regarding the current situation. As I said before, feel free to ask for more clarifications if need be.
Best regards,
Karim
=================================================== Karim Yaghmour karim@opersys.com Embedded and Real-Time Linux Expert =================================================== - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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