Christoph Hellwig has been, according to this web page, "in the top-ten list of commits to both the Linux 2.4 and Linux 2.5 tree". The page also mentions another fascinating piece of news, that he worked for Caldera for at least part of the time he was making those kernel contributions:
After a number of smaller network administration and programming contracts he worked for Caldera's German development subsidiary on various kernel and userlevel aspects of the OpenLinux distribution.
In 2002, he offered a paper on "Linux-ABI: Support for Non-native Applications" which is described like this:
The Linux-ABI project is a modification to the Linux 2.4 kernel that allows Linux to support binaries compiled for non-Linux operating systems such as SCO OpenServer or Sun Solaris. Back in 2002, he was described, in connection with his appearance at the Ottawa 2002 Linux Symposium, like this:
Christoph Hellwig So, in short, he was contributing to the kernel and working for Caldera on Linux/UNIX integration at the same time. His work for Caldera was on the Linux kernel ("he worked for Caldera's German development subsidiary on various kernel and userlevel aspects of the OpenLinux distribution"), and he also did work on his own on the kernel. Did Caldera know about his freelance contributions, in addition to knowing about his work for them? What do you think? He used his hch at caldera.de email address when doing it. All contributions to the kernel are publicly available anyway. They certainly could have known. As for his job, his signature on his emails back in 2001 was:
"Reverse engineering an advanced filesystem
Christoph Hellwig is employed by Caldera, working on the Linux-ABI binary emulation modules. In his spare time he cares for other parts of the kernel, often involving filesystem-related activities."
Christoph Hellwig He used the email address hch at bsdonline.org sometimes too, and
here you can see some of his Linux-abi contributions. Here and here are some of his contributions to JFS, Journaled File System [his email at Caldera shows here]. Yes, that JFS. Here he is credited as sysvfs maintainer, and he confirms it in this email, writing, "I've run native sysvfs tools under linux, but as now that I'm Linux sysvfs maintainer I'm looking into implementing free versions of it."
Kernel Engineer Unix/Linux Integration
Caldera Deutschland GmbH".
Here is a list of the operating systems that use or can handle the file system sysvfs:
"sysvfs: UNIX System V; SCO, Xenix, Coherent e21
operating systems that can handle sysvfs: FreeBSD (rw), LINUX (R), SCO (NRWF)
Here's a page listing by author (alphabetically by first name), with his emails to linux-kernel in June 2003, so he is still contributing.
Here he is listed on the Change log for patch v2.4.17. Here he tells Andrew Morton in 2002 that he will do sysvfs, using his hcd at infradead.org address. Here is an email in which he tells an inquirer how to contribute to JFS, including this tidbit:
I've run native sysvfs tools under linux, but as now that I'm Linux sysvfs maintainer I'm looking into implementing free versions of it. . . .
The JFS/Linux core team has setup a CVS commitinfo, but currently I'm the only one who receives it. And here he encourages someone to donate to the main JFS repository at IBM and talks about his role:
I'm one of the main commiters to JFS outside IBM and I'm really happy to see more people involved :) He also posts to the freebsd list as freebsd-fs at freebsd.org.
First I'd like to encourage you to contribute your userspace changes to the main JFS repository at IBM. For the 1.0.11 release I have added autoconf/automake support to easify portability and a bunch of portablity patches (mostly getting rid of linuxisms) is under way to the Core team.
Here is the press release when SCO in 2002 released "SCO Linux Server 4.0 for the Itanium (R) Processor Family" and which mentions that the product is based on United Linux. [Update: the link to the following 2001 LWN page referenced no longer resolves, so it has been removed:] This SCO page on LWN.net lists JFS as one of its features. Now, if you remember, SCO's Sontag was quoted as saying originally that they weren't talking about Linux, the kernel "that Linus and others have helped to develop. We're talking about what's on the periphery of the Linux kernel." Blake Stowell tried to correct that quotation later, but MozillaQuest insists that is what Sontag said.
This all relates to the affirmative defenses laches, undue delay, waiver, and estoppel, which we just covered. They will be hard-pressed to explain how they had an employee contributing to the kernel a couple of years ago, which they apparently assigned him to do, and yet claim they didn't know or didn't approve. If they didn't approve, why didn't they do a thing to stop it back then? Stop it? It was his job, judging from his title and his job description. And for that matter, the announcement about JFS was public on IBM's part, as we've seen, and Caldera didn't bring a lawsuit to block it back when it happened. That's the laches part.
As to waiver, allowing/condoning/permitting an action makes it hard to sue about the same action later. They are complaining that IBM contributed JFS to Linux, but their own employee, from this evidence, was involved in helping out. On the day IBM announced JFS was being given to Linux, Hellwig is listed as making five contributions to the kernel. All of this information is publicly available, so it was available to Caldera back when it happened.
I emailed Mr. Hellwig, to give him an opportunity to respond, but he says he can't comment, which is understandable. He's likely a great guy, and he's undoubtedly been a trusted Linux contributor, so this is nothing against him. It's about SCO and their position in the lawsuit, and it's about IBM's affirmative defenses. He's caught up in something through no fault of his own, from what I see. Caldera went in one direction, and then SCO suddenly shifted direction, leaving him hanging in the middle. I don't doubt that eventually we will hear from him, if only at the trial.
Update: Christoph Hellwig is listed with his Caldera Germany email address on the list of maintainers for the 2.4.28 Linux kernel for the following:
Wait. There's more:
P: Christoph Hellwig
The page lists an IBM employee as maintaining JFS, but here's Hellwig listed [PDF] with his Caldera email as part of the JFS team in a 2002 paper on JFS development.
P: Christoph Hellwig