I can hardly believe it. I’ve been in the EDA business since 1980 when I joined TI’s Design Automation Department after graduating from Cal Poly with my BSEE. Since 1995, much of my attention has been focused on EDA standards. I reached a moment of truth this year when I admitted, albeit reluctantly, that I could be called a standards-lifer. So, I decided it’s time to share my perspectives on what’s going on in the standards arena. Welcome to my blog - I can’t wait to hear from you! Liberty says goodbye to Si2, hello to IEEE ISTO
Posted by Karen B on May 16th, 2008
Yesterday, Synopsys announced that the ever-popular Liberty format for library modeling has moved from the auspices of Si2 (Silicon Integration Initiative) to the IEEE’s ISTO (Industry Standards and Technology Organization). In its new home, the Liberty Technical Advisory Board (LTAB) which oversees the format’s evolution will be able to include more members and ensure that Liberty can serve the needs of the IC design community for future generations of technology.  Not only have Magma Design Automation and Mentor Graphics joined the LTAB, but so has a major foundry.
It’s rather nostalgic for me to look back at how the Liberty format has moved through its standardization paradigms. As a leader in the electronic design automation industry, Synopsys strives to make the necessary EDA standards available through the most effective standardization processes and organizations (which keeps me quite busy, I must say).
When I first joined Synopsys 13 years ago, our library format – known as “.lib” back then – was a closed, proprietary format. The format was developed around 20 years ago as part of Synopsys’ original product offering, Design Compiler for logic synthesis. It was a Synopsys-only format for 10 years or so.
Customers began experiencing the need for an open library modeling standard as they built design systems with tools from various vendors as well as their own homegrown special-purpose applications. The first step by Synopsys towards making .lib accessible to other EDA companies was via an open, company licensing model. Anyone could use the format after obtaining a license from Synopsys. Many companies took advantage of the opportunity to license and use our library format.
One day, my manager walked into my office and said, “Karen, I want you to open source .lib.” I thought he was crazy – EDA formats were simply not made open source.  That was for operating systems and software. Yet, it didn’t take us long to recognize that this revolutionary way of standardization would be useful (not to mention fast – back then, EDA format standardization was notoriously slow) for our customers and other EDA suppliers. Renamed “Liberty”, our library format was made available to everyone who used a “click-through” GPL-based license. Downloads of the Liberty format soared, and the method of creating EDA standards through open source was launched in the industry.
After about 6 years of Synopsys overseeing the evolution of Liberty, we moved it into an Si2 coalition called the Liberty TAB (Technical Advisory Board). There were 12 founding member companies of the board who directed enhancements of the format which was still available by means of its open source license.
Liberty stayed with Si2 for 2 years and has now moved to the next stage in modern standardization. Under the IEEE ISTO, the Liberty TAB will enjoy another level of freedom (excuse the pun) in evolving the popular standard. Liberty remains available through open source to everyone and continues to be the most widely-used library format in the semiconductor industry.
Not only has the Liberty format itself been improved over the years, but so has the process in which it is standardized.Â
RSS
I’ve been following EDA format standard and this is a great progress. I also like the way Karen described her discussion with her manager to make it open.
Would you share with us the impact of this change for customers?
Does it mean that future Synopsys update must be reviewed with IEEE before it is released ?
Unrelated question:
Any comment on OA and Milkyway standard? How about LEF/DEF?
Two points
1. How is Open Source is a good thing where .lib is concerned and not a good thing in the context of VMM. It was interesting to see these consecutive posts from Karen – trying to justify both positions as being great for Synopsys
2. The change of .lib from Si2 to being contractually administered by ISTO does not change the control of .lib. Synopsys continues to have veto on what goes into .lib. Why not actually donate it to the IEEE instead of pretending to do the right thing by calling it the “next stage in modern standardization”?
This is really great news. Open source means that things are as open as they possibly can be (copyleft be damned). It’s good to see Mentor and Magma and foundries all working together with the IEEE and Synopsys to make Liberty even better. I hope VMM becomes open source as well. Then people will use is as broadly as they do Liberty.
Ronald,
Customers shouldn’t see any impact on Liberty’s move to the IEEE ISTO. Updates will still be made regularly and will be still be available on http://www.opensourceliberty.org. The review process is similar to what it was in Si2, via the Liberty Technical Advisory Board. The IEEE itself is not introduced into the process. The positive change is in the LTAB – there is now more room for a balance of foundry, EDA, and end-user representation.
As for OA and Milkyway, we see OA as very important in the analog/custom market. As a matter of fact, the Interoperable Pcell Library initiative is able to capitalize on OA to promote choice in analog design flows. Milkyway continues to be the foundation for Synopsys’ digital design platform (Galaxy).
We will continue to support LEF and DEF for at least the near future. The latest version we support is 5.6. Si2 controls the evolution of the Cadence LEF/DEF format.
Kevin and Charles,
VMM open source request noted.
Kevin,
What do you think of the OpenAccess model in Si2?
Karen and Kevin,
Do you mean the Si2 agreement under ?
http://www.si2.org/openeda.si2.org/Licenses/lic_files/OpenAccessInternalUseAndDistributionLic_v4_041001.pdf
I have a hard time figuring out which one you guys mean since there are many different ones used by Si2 under
http://www.si2.org/openeda.si2.org/Licenses/
Charles,
I was referring to the Si2 OpenAccess process in general (instead of a user agreement), where an architect has veto power over proposed changes. I wondered about Kevin’s perspective on this.
Karen
Where can I find the info about the veto ? It’s not in the license. According to the license, anyone licensee can make changes to the package as they send their changes to SI2 in 30 days. The only icky thing is it looks like your have to be some kind of uber-member and stay some kind of uber-member of SI2 if you want to distribute the code to others, even in binary format. Not really open-sourcy. Some kind of commercial developers thing like Apple or Micro$oft.
Karen,
I just discovered an open source 45nm library that uses Liberty from links from SI2. It seems very useful since it includes virtually everything including SPICE models and .lib.
http://www.nangate.com/index.php?option=com_content&task=view&id=137&Itemid=132