Virtual prototyping methodology to boot Linux on the ARM Cortex A15

Design teams don’t need to accept inaccuracy or wait until design freeze if they use a virtual prototype. Software from Carbon Design Systems, for example, allows engineers to do advanced performance optimization by leveraging ARM Fast Models for speed and Carbon’s Swap & Play™ technology for 100% accuracy. The integration with ARM Fast Models enables an engineer to increase simulation performance in selected components during periods of time when accuracy isn’t critical. Swap & Play then enables ARM Fast Model components to be swapped out in favor of their 100% accurate equivalent components when accuracy is required, such as benchmarking. Essentially, this means performance when it’s wanted and accuracy when it’s needed. 

In the system illustration below, the engineer used the Cortex-A15 Linux Carbon Performance Analysis Kit (CPAK) to accelerate analysis, optimization and verification of the SoC’s performance. The CPAK contains reference hardware and software designs along with analysis and debug software for the Cortex-A15 processor, a way for him to immediately begin analyzing performance and power constraints.

Figure 1: The Cortex-A15 Linux CPAK was used to accelerate analysis.

After booting the Linux kernel provided the CPAK, the engineer created a Swap & Play checkpoint corresponding to the start the Dhrystone benchmark. Instead of simply swapping over to cycle-accurate execution at that point, however, he continued running in the Fast Model-based system. He used SoC Designer Plus’ built-in checkpoint manager to create a variety of additional checkpoints, each representing different benchmarks or interesting points of execution.

To obtain accurate results, he then loaded each of the checkpoints into the cycle-accurate implementation of the CPAK and completed the benchmark execution. This enabled him to pinpoint certain areas of the benchmark for deeper analysis without needing to execute the entire benchmark in cycle-accurate mode. The screen shot below gives a small sample of the system profiling statistics that can be gathered while running the benchmark.

Figure 2: The virtual prototype is tracking several hardware events and statistics running a benchmark on top of an operating system.