Git serves as an important distributed version control system, designed for software engineers to preserve comprehensive history of changes and provide advanced operations for efficient project management. This feature makes Git an ideal tool for software development, enabling teams to house an entire project within a single repository.
However, adapting Git for hardware design poses distinct challenges, as the requirements and workflows significantly differ from software development.
The Evolution of Version Control Tools
Silicon Valley venture capitalist Marc Andreessen proclaimed “Software is eating the world” in 2011. And software complexity has continuously escalated, necessitating more iterations, managing larger files, collaboration across global teams, and higher data volume to store.
Initially, version control tools like RCS and SCCS provided basic revision management for individual files. They store the code base history on the same disk storage used for the code under development. Each directory is tracked separately. As a result, those initial version control tools fell short in handling the entire software projects. This gap led to the creation of wrappers such as Concurrent Versions System (CVS) in 1986.
As software development extended over multiple sites and needed more sophisticated configuration management, client-server systems like ClearCase and Perforce became popular around the early 90s. They offer more advanced branching and merging functions and offload storage from the local disk to networked file storage.
With the growth of the open-source Linux Kernel, the Linux community built their own version control tool, Git, in 2005, to handle distributed development of large open-source projects.
Challenges of Configuration Management in Semiconductor Engineering
With today’s semiconductor design scales to a team of thousands of engineers, the challenges of configuration management extend beyond software development. Fields such as integrated circuit (IC) design and semiconductor engineering confront similar challenges, including:
- Managing numerous iterations.
- Storing vast collection of sizable files.
- Collaborating with multiple stakeholders.
Accurately tracking revisions and configurations is crucial in these contexts, highlighting the need for efficient version control systems tailored for hardware engineers.
But what is an ideal version control solution for managing projects in IC design domains and workflows?
Semiconductor Design vs. Software Development: What Is the Difference?
Semiconductor design and software projects share common ground.
First, both involve extensive collaboration among multiple engineers who create, debug, and refine a plethora of files across multiple iterations. This process necessitates a seamless solution for team members to exchange updates, including the creation of releases, patches, and variants as the project progresses.
Despite these similarities, semiconductor design diverges significantly in its data type, workflows, and requirements.
Data types
Digital designs are typically done using text files written in Register Transfer Level (RTL) language, such as Verilog. However, there are other analog, custom, and packaging components specialized graphical tools, like schematic and layout editors. These graphical tools produce a suite of related files, often encompassing large binary files to represent design objects, marking a clear departure from the typical software development workflow of editing, compiling, and debugging.
Workflows
The semiconductor design flow introduces a higher level of complexity, incorporating various stages such as synthesis, placement and routing, simulations, formal verification, and timing analysis. Each stage requires specific expertise and generates a significant amount of, often binary, files necessitating meticulous version control.
In comparison, a software workflow involves a loop of edit, compile, and debug where the compile step may sometimes not be necessary.
Execution
Throughout the IC design flow, some components may be reusable in whole or in part, typically referred to as Intellectual Property (IP) blocks. Companies either develop IP internally or procure it from third-party vendors such as Arm and Synopsys. Semiconductor IP is the fundamental functional block for today’s SoC or chiplet designs. Effective IP management demands not only an accessible IP catalog but also advanced revision control, access control, and traceability across design hierarchies.
Git works very well for managing software development, with each engineer working on developing a feature or fixing issues. Its powerful ability to merge changes to text files enables truly efficient distributed development, especially for open-source projects. However, does Git meet the requirements of semiconductor design?
Six Challenges of Using Git for IC Design Data Management
No.1 Handling large files
IC design has exceptionally large files from hundreds of megabytes to gigabytes. The Git’s model requires users to clone the repository. As a result, every IC designer on the project needs to create a copy of all the large design files and all the revisions. This approach becomes impractical due to the storage implications, especially when considering the costs of high-availability network storage in a corporate setting.
No. 2 Binary file management
The inability to automate merging for schematics and layouts needs a centralized repository to prevent manual merging errors. Such a setup promotes synchronization among multidisciplinary engineers, enhancing collaboration and efficiency.
No. 3 Geographical distribution
Design teams are often geographically distributed. The teams need to synchronize their changes daily or more often. Technology such as cache servers is necessary to make this more efficient especially given the size of the design data.
No. 4 Access control
As design objects are often stored as a collection of co-managed files, a configuration management system should recognize these as related and manage it as a single, user recognizable, composite design unit.
Individual engineers or contractors have different responsibilities in the same design project, requiring the system to have proper access controls in place. For instance, you may want to make sure that a layout engineer doesn’t change a schematic design. You may also want to prevent contractors from having any access to sensitive libraries. To enforce access controls, you need to have project data managed by a centralized server.
No.5 Design hierarchy management
Unlike software development, where data is often organized in a simple flat directory structure, IC (Integrated Circuit) design involves a complex hierarchy of blocks. Each level of this hierarchy relies on integrating a lower-level block, making the organizational structure critical for IC designers. To manage these intricate designs, IC designers require a robust configuration management system capable of handling and executing within this hierarchical framework. Imagine the challenges software developers would face without the ability to compare different versions of their files to spot changes. Such a scenario would make it extremely difficult to review modifications or pinpoint the source of new bugs. Similarly, IC designers and layout engineers should have access to advanced tools that enable them to detect differences between versions of schematics or layouts.
No.6 Design tool Integration
The most challenging requirement for IC design data management is that revision control and configuration management features must seamlessly integrate into the design tools. In addition to efficient processes, design tools must be aware of the configuration management system to make sure that design changes are correctly recorded and trackable.
Streamline IC Design Data Management with Keysight SOS
There’s often a strong temptation to look for tools that already exist and shoehorn them to meet similar needs in a different domain. However, while Git and other software configuration management (SCM) tools fit well with software development, they fall short in specific requirements of IC design, from binary file management to design tool integration.
Keysight Design Data Management (SOS) is a system designed from the ground up to meet the unique requirements of semiconductor IC designers.
Keysight SOS can recognize composite design objects, understand IC design hierarchy, and reduce network storage through smart cache. Most importantly it has seamless integration with all major EDA (Electronic Design Automation) tools including Cadence Virtuoso Studio, Synopsys Custom Compiler, Keysight ADS (Advanced Design System), and more.
Director of solutions strategy
Keysight Technologies
