how can I run gem5 with vxWorks, please give me your advice ,thanks

[Lvhoujun]

how can I run gem5 with vxWorks, please give me your advice ,thanks

[BobbyRBruce]

Do you mean running vxWorks inside a gem5 simulated system?

I'm not familiar with vxWorks by i suspect it'd be quite hard to do. You'd need to create a kernel and disk image containing the vxWorks operating system. Then you'd need to construct your simulated system to load the OS via the kernel and disk image.

[BobbyRBruce]

I asked our ChatGPT bot about this. I broadly agree with this high-level plan, though strikedthrough parts I thought were wrong and/or unecessary and added additional test in bold.

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Running vxWorks, a real-time operating system, inside a gem5 simulation involves several steps, primarily focused on setting up the appropriate environment and configuration within gem5. Here's a general guide to help you run vxWorks inside a gem5 simulation:

1. Obtain vxWorks Image

Firstly, you need a vxWorks disk image that is compatible with the architecture you plan to simulate in gem5. This usually means having a vxWorks kernel image compiled for the specific target architecture (like ARM, x86, etc.).

2. Choose the Correct gem5 Configuration

Select a gem5 system configuration that matches the architecture for which your vxWorks image is built. For instance, if you have a vxWorks image for ARM, use an ARM-based system in gem5.

3. Prepare gem5

Make sure you have the latest version of gem5 or at least a version known to be compatible with the vxWorks version you intend to use. You'll need to configure gem5 for full-system simulation, as vxWorks will run as if on real hardware.

4. Kernel Configuration

If necessary, configure the vxWorks kernel to ensure it's compatible with the simulated hardware in gem5. This might involve adjusting settings related to hardware components like CPUs, memory, or peripheral devices.

5. Create a Disk Image

If vxWorks requires a disk image (for example, to load additional modules or configurations), create and configure this disk image accordingly. This step might involve mounting the image on your host system, copying necessary files, and then unmounting it.

### 6. Network Configuration (Optional)
If your simulation requires network capabilities, configure the network settings in both vxWorks and gem5. This could involve setting up a simulated network in gem5 and configuring vxWorks to use this network.

7. Write a gem5 Simulation Script

Write a Python script for gem5 that sets up the system configuration, including CPU type, memory size, disk images, and any other hardware parameters relevant to your vxWorks image. This script will be used to start the simulation.

This is a big step! You may have a to define a very specific system to get vxWorks working. As mentioned in my original reply, I'm not familiar at all.

8. Booting vxWorks

Use your gem5 script to boot the vxWorks image. You will need to specify the path to the vxWorks kernel image, and any additional flags or parameters required for booting , and the path to the vxWorks disk image.

9. Debugging and Troubleshooting

Be prepared for potential issues during the initial setup. Debugging tools in gem5, like DPRINTF in C++ and print() in Python, can be helpful. Ensure that the simulated hardware configuration matches the expectations of the vxWorks image.

10. Run the Simulation

Once everything is set up, run the gem5 simulation. Monitor the simulation for any errors or unexpected behavior, and make adjustments as necessary.

Additional Notes

Running a specialized operating system like vxWorks in a simulator like gem5 can be complex and may require specific adjustments depending on the exact version of vxWorks and the simulated hardware configuration. The steps outlined above provide a general framework, but be prepared to adapt them to your specific needs.

[Lvhoujun]

Thank you very much, I got the points you've mentioned. But I don't know how to write vxWorks BSP package according to the gem5 hardware configs, and I'm not sure what kind of hardware borard gem5 using,just got few hareware infomations on this file gem5/src/dev/arm/RealView.py, even so, the vxWorks BSP still stops me

[hnpl]

Disclaimer: I have no idea how vxWorks works or how to create vxWorks BSP. My understanding of how vxWorks boots is via this documentation [1].

In gem5, when you run a full-system simulation for ARM and RISC-V, there'll be a file called m5out/devices.dtb that will be generated at simulation time. This file contains a Linux-compatible device tree that has specifications of all gem5 hardware components. This device tree will be written to a specific address in the memory before simulation. The address of where the device tree will be loaded is known by the bootloader, which will read the device tree.

The bootloader + kernel workflow in gem5 is that,

• The bootloader will be written to the memory system at a specific address. The bootloader should know the addresses of the kernel and the device tree.
• The kernel will be written to the memory system at a specific address.
• The device tree blob will be written to the memory system at a specific address.
• After all the above steps are done, the gem5 simulation will start with the first PC being at the start of the bootloader.

So, I think the first step is to run gem5 simulation with your target system, then you can obtain the device tree and start working on booting vxWorks.

I think you can do something along this line to write the BSP.

Another note: if you are able to use a bootloader to boot a kernel in QEMU, I think gem5 can do the same.

[1] https://docs.u-boot.org/en/latest/usage/os/vxworks.html#vxworks-bootline