Portability X86 Emulator Translates Instructions And System State Implementation Framework

In the past thirty years, the business servers and personal computers based on x86[7] architecture has an overwhelming advantage in the market, being compared with other architectures[8]. But recently, with the rising demand of mobile devices such as smart-phones and tablets, the RISC[1] CPUs (lead by ARM[4]) become more and more popular. Besides, regarding national security and technology development strategy. China has also developed some RISC processors such as Loongson[26] and MPRC Unicore-2[27]. To the RISC CPUs like ARM, Loongson and MPRC Unicore-2, the capability of its compatibility for existing x86 software makes it easier for them to be accepted by people.In order to make x86 software be capable of running on other architectures, x86 emulator is invented. The x86 emulator is programmed to be running on non-x86 architectures and creates a virtual hardware environment which fits x86 standard. The software for x86 can then be run in the virtual x86 environment on other CPU architectures.Currently, all the x86 emulators which support host platform of multiple CPU architectures run in user-level, and the system-level x86 emulators are designed for dedicated CPU architecture. So, system-level x86 emulator for China-designed CPU needs to be developed.This article is going to introduce a highly portable x86 emulator, its dynamic instruction translator and its framework for implementation on system-level. Its name is PEX86 (Portable Emulator for x86). PEX86's dynamic instruction interpretation technology has good portability. PEX86 is designed to run on the system-level of host machine, which means it manages all the hardware resources by itself, without the support from any operating system. Because emulating the whole x86 platform in software requires large quantity of work, the current phase of PEX86 only supports emulation of x86 real-mode. But it's a solid foundation for future emulation for x86 protected-mode.This article has the following contributions:1. It explored the solution for compatibility from China-designed CPU to x86 operating systems and applications. 2. It used portable dynamic instruction interpretation technology and software framework for system-level implementation. This enables PEX86 to support host platform of different CPU architectures.3. Its system-level implementation framework used functional layering and modulation, which makes the mapping from virtual peripheral component to host peripheral component agile and configurable, it also makes the work to add and edit a virtual peripheral component easy.