1 COMP427 Embedded Systems Lecture 3. Virtual Platform Prof. Taeweon Suh Computer Science Education Korea University

2 Virtual Platform Virtual Platform is a software model of a whole computing system  Virtual Platform is very widely used for software development much before hardware is ready The target computing systems of virtual platform have been SoCs (System-on-chip), but it can be used for future PC systems Don’t be confused with Virtual Machine!  VM allows the sharing of the underlying physical machine resources between different virtual machines, each running its own OS  The software layer providing the virtualization is called a virtual machine monitor or hypervisor x86 provides several instructions for virtualization COMP427

3 Virtual Platform (Cont.) Your PC SoC model in 2010 PC system model in 2010 Software models Software running on new products BIOS, Firmware and OS development Validation software development Firmware and RTOS porting to SoC Applications on SoC COMP427

4 Virtual Machine Example: Xen COMP427

5 SoC Market Dynamics Source: Synopsys SNUG: Synopsys Users Group COMP427

6 SoC Design Challenges Source: TLM2.0 presentation from CoWare COMP427

7 Software Determines Project Schedules Source: Synopsys COMP427

8 Advantages of VP Source: Synopsys COMP427

9 How is it different from simulators? In a broader sense, all the simulators may be viewed as virtual platform  Benchmarks and testvectors are running on virtual models (simulators) However, simulators tend to model only specific components rather than a whole system (platform)  For example, Simplescalar doesn’t model peripheral devices. So, it is not feasible to run BIOS, DOS, OS (Windows) COMP427

10 How fast VP should run? Performance comparisons & VP requirement  Hardware simulation (RTL) Concurrent modeling ~ IPS (Instruction / second)  Hardware emulation Porting RTLs into reconfigurable machine (array of FPGAs (Field Programmable Gate Array) KIPS ~ MIPS depending on what you emulate  Virtual platform ~MIPS We want to run real- applications on top of OS in reasonable time COMP427

11 How to model VP? Depending on the level of accuracy you want to achieve and your goal, there are different levels of abstractions Level of abstractions  Cycle accurate model (CA) Verification and HDL co-simulation  Programmer’s view model (PV, we focus on PV) Highly abstracted mode Register accurate model Functionally correct COMP427

12 What Language to model VP? Verilog-HDL and VHDL  Used to model cycle-accurate model  Too slow (~IPS depending on complexity) C, C++  Used to model PV in general  Also can be used for cycle-accurate modeling COMP427

13 In this class…. We are going to use a software model for a small SoC (AT91) from Amtel  COMP427