Linux Snag Irks Oracle

Oracle is fast losing its patience with both XenSource and VMware.

Oracle is fast losing its patience with both XenSource and VMware over their reluctance to work together to develop a single interface that will integrate a variety of virtualization solutions in the Linux kernel.

"We certainly believe in one simple, universal way to integrate a variety of virtualization solutions, and that is the way that Andrew Morton [the maintainer of the stable Linux kernel] wants to go," said Bob Shimp, vice president of Oracles technology business unit, on July 31 in Redwood Shores, Calif. "I can say that Oracle is losing its patience over this issue, and we are going to be pushing harder and harder on everybody to come to the table with a realistic solution."

Oracle is a significant player in the open-source community and, as both an open-source and commercial database provider, has a strong interest in getting virtualization technology into the kernel. It recently managed to get the Oracle Cluster File System technology, an open-standard file system, adopted as part of the Linux 2.6 kernel, the first such technology to be included in the kernel.

Oracles comments come hot on the heels of those made on July 26 by Greg Kroah-Hartman, a Linux kernel maintainer for a number of subsystems and a maintainer of the stable Linux kernel team, at the annual OReilly Open Source Convention, or OSCON, in Portland, Ore. Kroah-Hartman said XenSource and VMware are butting heads instead of working together toward a joint solution.

"Xen and VMware both supply huge patch sets and are both trying to do the same thing, but their technologies dont work with one another. … We want them to talk and work it out," he said.

Despite mediation by neutral parties from the Linux distributions, the community and vendors, a solution is not coming any time soon, Kroah-Hartman said.

The initial plan was to merge the Xen patches into the Linux kernel, which would then have run only on Xen. But there has also been a move toward an interface in the kernel that would let it work with any virtualization hypervisor technology. Xen, VMware and Microsoft are all working on hypervisor technologies.

While Brian Byun, vice president of products and alliances for VMware, acknowledged that the Palo Alto, Calif., company has been approached by a neutral third party about offline mediation to establish how best to make this happen, he said he was unaware of any previous request for the company to meet directly with XenSource on this.

Byun recently blogged that VMware hopes there will soon be a standard Linux interface for paravirtualization—a virtualization technique that presents a software interface to virtual machines that is similar but not identical to that of the underlying hardware—which would simplify and standardize how Linux is supported on various hypervisors, including VMware and Xen.

"VMware is actively working with the Linux kernel community to de--velop an open interface so that the Linux kernel can run natively and efficiently on a choice of hypervisors," Byun said. "Such an interface would also be available to any operating system."

VMware made its initial proposal for such an interface available to the Linux community and is pursuing Linux and hypervisor interoperability, not as a commercial arrangement but within the open, transparent and merit-based multivendor approach, he said.

While Byun stressed that VMware has been working closely with the Linux kernel community on the proposed Linux virtualization interface, he did acknowledge that its proposal is different from that which XenSource has implemented.

"We have told the kernel community exactly what our proposal is and what characteristics we believe a solution has to have for the Linux maintainers and customers," Byun said. But VMware is not keen on meeting directly with XenSource, as it believes there should be multiparty discussions around the best solution for a common Linux virtualization interface, and those discussions should take place in an open forum such as the kernel mailing list. "That is more productive than a back-room, one-to-one discussion between two commercial companies," Byun said.

For his part, Simon Crosby, chief technology officer for XenSource, of Palo Alto, said that while there had historically been a "degree of head butting, we are well beyond that now." But he rules out any mediation, saying that this is "not an issue at this stage, as it is not about marketing or a public fight. Everything Ive seen on the part of the engineering teams of both companies indicates a commitment to solving real technical issues," Crosby told eWeek.

Linux virtualization war: VMware versus Xen

VMware Virtual Machine Interface proposal:
  • Lets VMI hook the hypervisor into the kernel at load time
  • Never exposes the hypercall API itself or any of its closed-source code
  • Enables the same kernel to run virtualized or native
    Xen proposal:
  • Kernel can link with Xen or with a shim that offers the same hypercall API, allowing the Linux kernel to run natively
  • Uses an open API, allowing kernel developers to see and work with the code to virtualize the kernel
    Source: eWEEK reporting