IBM and Sun Microsystems have made a deal related to operating systems, the long-time rivals have revealed.

Neither company offered any details on the news, set to be announced this evening UK time, except to say that it concerns an "operating system agreement."

Sun has only one operating system technology: Solaris. The company has been trying to promote Solaris as an open alternative to Linux, whose popularity severely cut into Sun's bottom line in the early part of this decade. But Sun has so far failed to rally much support from rival server vendors like IBM, Hewlett-Packard or Dell.

Sun president and CEO Jonathan Schwartz and IBM hardware group chief Bill Zeitler will host the call, indicating that IBM may be ready to support Solaris on its Intel-based line of servers, which it calls System x and BladeCenter systems.

In fact, IBM has listed Solaris as one OS option for System X and BladeCenter systems on its website since May, according to the Internet Archive website.

It would be a big step for IBM, since the company has historically been a major proponent of Linux.

The company, however, also sells the Windows OS on its Intel systems.