…if an organisation distributes products based on the modified design, it must publish those changes.
The GPL serves as a convenient check on rivals who might want to profit from Sun's multicore investments by wrapping their own interface on a Sun Niagara core, Yen said.
"With the GPL, if our direct competition — IBM, Intel and AMD — wants to copy what we have done in high thread count per core, they will have to put [their changes] back. That will potentially be a barrier to just copying what we've got," Yen said. Those rivals might be leery of revealing not just their own designs, but also might be forbidden from revealing third-party intellectual property, he said.
Cores and threads
Sun's Niagara chip is the industry's most aggressive example to date of general-purpose multicore chips — those with multiple processing engines on each slice of silicon, as opposed to the comparatively old days when each chip had only a single processor engine. Niagara has eight cores, and each core can process four instruction sequences called threads.
Niagara 2 still has eight cores, but each can handle eight threads, and the chip has better number-crunching abilities, as well as built-in encryption, input-output control and 10-Gbps networking. Niagara 2 servers are due to ship in the third quarter of 2007, Sun chief executive Jonathan Schwartz said in April.
Sun recognises that this multicore, multithreaded approach isn't easy for some necessary partners in the software industry to digest. Trying to encourage their support is another reason Sun opted for the OpenSparc project.
There are many success stories in the world of software, and we believe that it is time for something similar to happen in the hardware world
Fabrizio Fazzino, designer, Simply RISC
"We strongly believe this multicore, multithreaded direction is the way to go, both for efficiency in computing and efficiency in power consumption," Yen said. "But this cannot be done alone by hardware processor vendors. It requires the software community, all the way from system software to application software, to adapt and participate," he said. "By open-sourcing OpenSparc S1, it's also sending strong signals urging the IT community to go in that direction."
But it's notable that the two companies so far working on open-source derivatives aren't as bold. Both Polaris Micro and Simply RISC have designs with a single four-thread core.
There are complications to making Niagara 2 an open-source project. One of them is export control, because the US Government imposes restrictions on encryption technology.
"Suppose today I want to publish an implementation of elliptic curve cryptography algorithm. I'm not sure the government will allow us to do that," Yen said. "There are more things we have to work out, clarify, maybe get certain permissions."
Programmable chips
Making a chip design an open-source project is a very different beast compared with open-source software projects.
It's easy to get a computer, download some software source code, and start programming away. But when it comes to hardware design, fewer people have expertise, and a chip foundry isn't likely to be interested in allocating fab capacity to build a handful of some amateur's experimental processors.
But for would-be open-source chip designers, there's another way: field-programmable gate arrays, or FPGAs. These programmable chips are blank slates, from companies such as Xilinx, onto which designers can load whatever hardware logic is desired.
To that end, Sun has released a version of OpenSparc that runs on an FPGA, said Shrenik Mehta, Sun's senior director of the OpenSparc programme. The design has just a single core with a single thread so students can figure out ways to beef it up, he said.
"It works like a building block, so students can experiment in the lab or course work to do different designs with one core and two threads, two cores, etc," Mehta said.
Indeed, that's just what the University of California at Santa Cruz is doing in one of its courses. Sun established a centre of excellence at the university to try to foster collaboration, and a UC Santa Cruz assistant professor, Jose Renau, is a member of the OpenSparc community governance board.
Although Sun is pleased with the open-source chip effort so far, including 4,700 downloads of the design, the company recognises that progress so far is at an early stage.
"Though the publicity is getting broadened," Yen said, "most people are still digesting and trying to understand what we are offering."
