Sun has finally released its Janus software that lets Solaris run Linux apps.

Rewritten and renamed BrandZ, it has been provided to Sun's OpenSolaris community a year later than expected.

The project has expanded in the interval and it can now be used to run operating systems including FreeBSD and Apple open-source Darwin project, said Nils Nieuwejaar, the Sun engineer who is technical lead on the project.

Janus was pulled from the Solaris 10 release earlier this year when Sun engineers decided that it would be better to redesign the software to work with Sun's new virtualisation technology, called Solaris Zones. "It made much more sense to approach the problem that way," he said. "It was actually cool that after talking about Janus for so long, management was actually able to let engineering pull Janus when we felt it wasn't ready."

Sun hopes to eventually support specific Linux distributions, including those of Red Hat and Novell, said Tony Iams, senior analyst with research firm Ideas International. "They're not just going to make this a generic Linux capability. This is actually going to be supporting very specific Linux distributions," he said.

Because Solaris users will need to install the version of Linux that they want to use with BrandZ, they will need to buy support licenses in order to get compatibility with products like Red Hat Enterprise Linux, Nieuwejaar said. That means that commercial Solaris users will be looking at two separate support licences.

Sun is currently in negotiations with Red Hat over licensing terms, said Chris Ratcliffe, Sun's director of Solaris marketing. "We would hope to come up with a cheaper alternative than purchasing support for an entire Red Hat operating system"