The pact has been very profitable for both companies, said ITIC principal analyst Laura DiDio. “It gives [Microsoft] a presence in the open-source world, however unwelcome it is to some folks.”

SUSE Linux has led to a resurgence for Novell, and the operating system ranks second only to IBM’s AIX version of Unix for having the least unplanned downtime in ITIC’s reliability studies, DiDio added. “It’s not like Microsoft is wed to an albatross.”

Controversy surrounding the indemnification agreement inspired a provision in the GNU General Public License v3 that bars similar patent agreements going forward.

“Generally speaking, most software companies have attacked each other with patents; software patents are quite a drain on productivity of the software industry in this regard,” said Bradley Kuhn, a policy analyst and tech director at the Software Freedom Law Center, which provides legal services to Linux companies.

“But I am not readily aware of anything specific between Novell and Microsoft before their deal. If it was a large enough dispute that it made it to court, the court records would presumably show if there was.”