Tests by IT Week Labs indicate that vendors and users could easily re-compile their Linux software to temporarily remove modules that may contain SCO copyright software, and so avoid potential demands for royalty payments.

Support contracts permitting, modules could be replaced by alternatives that do not infringe SCO's copyrights, ensuring that levels of functionality are maintained.

However, the tactic will not be feasible until SCO itemises the Linux components at issue in its lawsuit with IBM.

Chris Sontag, senior vice president of SCO's SCOsource intellectual property division, said, "It is possible to produce a distribution that does not infringe SCO copyrights." But he added that it would be more than just a question of removing a few lines of code. "There are major elements in the 2.4 kernel. For example, Oracle would not run on a 2.2 kernel and perform effectively," Sontag said.

However, Joe Eckert, vice president of corporate communications at Linux distributor Suse, said the task would not be so complex. "That code could be replaced within weeks if not days," he said.

But according to experts, it would be impossible to say for certain which applications would be affected until SCO lists the modules that it claims infringe its rights.

In our tests, removing binary emulation modules had no discernible effect on the most popular Linux applications, such as Apache, Sendmail and Linux firewall tools. We selected these modules because SCO cited similar software in its complaint against IBM, in March.

We recompiled the kernel on a Suse Linux 8.2 system, which uses the 2.4.20 kernel, to remove all binary emulation modules. These modules enable legacy Unix applications to run on Linux servers, including applications originally developed for Unix SVR3- and SVR4-compatible systems. Related modules support UnixWare 7.x and SCO OpenServer apps.

Analyst Butler Group has said it is only a matter of time before SCO code is removed entirely from the Linux kernel. "Even if SCO's claims are proven to be true, that the 2.4 kernel and later do contain Unix code, the kernel will be rewritten," wrote the firm in a recent research note.

"A new kernel will not be long in coming, and SCO can wave goodbye to its expected royalties."

The IT Week Labs findings come as a US software company said it will release a tool to root out SCO code and replace it.

Aduva said it will customise its OnStage 2.0 product so that it can conduct a complete system inventory to identify SCO code and automatically replace it, once the code is identified. Aduva also offers a free Linux health check at the web address below.

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