Introduction

About GNATemulator

Simulators are useful tools in many respects. Installation, setup and deployment to a development team will prove to be easier and quicker than with a real target. Simulator usage on a native platform will also bring more flexibility in the development of the application.

GNATemulator is particularly suited for functional testing and unit testing. It allows for efficient target code execution. It simulates a simple board and does not aim at complete board simulation. This should be mostly transparent to the application developer as the differences between the real target and the simulator should be handled and hidden by the platform provider.

Product Content

The product contains three components:

  • The Simulator: This is the heart of the product. The main tool is called gnatemu and is prefixed by the relevant target name. Under the hood it relies on the QEMU processor and board simulator. GNATemulator efficiently runs the executable: the target code is translated on the fly, one basic block at a time, to the host processor. The translated code is then kept in a cache so that no new translation is required when the execution passes through a basic block that has been executed. An important point to keep in mind is that GNATemulator is translating and executing instructions as fast as possible and thus won’t be cycle accurate. The clock used by GNATemulator is the host system clock. Timing events are thus dependent on that clock and will not reflect the timing characteristics of a real target board.

  • GNAT Bus: A native framework to emulate devices (see Extending GNATemulator chapter).

  • The examples: For each supported platform there are examples that can be used as a reference for further development with GNATemulator

Note on the Documentation

As mentioned in the previous section the main tool name is:

<target>-gnatemu

Always replace <target> by the relevant target prefix in your context. As a reminder here is the list of target supported by GNATemulator along with the expected tool name:

Platform

Tool name

AARCH64 ELF

aarch64-elf-gnatemu

ARM ELF

arm-eabi-gnatemu

AVR ELF

avr-gnatemu

LEON 3 ELF

leon3-elf-gnatemu

PowerPC ELF

powerpc-elf-gnatemu

RISCV32 ELF

riscv32-elf-gnatemu

RISCV64 ELF

riscv64-elf-gnatemu