# Run the Linux software stack on an FVP

## In this learning path

- [Introduction](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/)
- [Introduction to Arm Fixed Virtual Platforms (FVPs)](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/intro/)
- [Configure Trusted Firmware-A build flags to include cpu_ops support](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/steps/)
- [Modify the device tree for CPU FVPs](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/modify/)
- [Run the Linux software stack on an FVP](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/run/)
- [Debug the software stack](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/debug/)
- [Next steps](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/_next-steps/)

## Launch the Linux software stack on an FVP
Once you’ve built the Linux stack with the correct configuration, you’re ready to run it on an Arm CPU Fixed Virtual Platform (FVP).

Replace `<SRC_PATH>` with the root path to your workspace, and `<PATH_TO_LOG>` with the location where you want to save the UART output logs.

## Verify the build output
After building, check the output directory to make sure the expected files were generated:

```
tree output/aemfvp-a/aemfvp-a/
```

The expected output is:
```
__output__
output/aemfvp-a/aemfvp-a/
__output__
├── Image -> ../components/linux/Image
__output__
├── Image.defconfig -> ../components/linux/Image.defconfig
__output__
├── fip-uboot.bin
__output__
├── fip-uefi.bin
__output__
├── fvp-base-revc.dtb -> ../components/linux/fvp-base-revc.dtb
__output__
├── tf-bl1.bin -> ../components/fvp/tf-bl1.bin
__output__
├── tf-bl2.bin -> ../components/fvp/tf-bl2.bin
__output__
├── tf-bl2u.bin -> ../components/fvp/tf-bl2u.bin
__output__
├── tf-bl31.bin -> ../components/fvp/tf-bl31.bin
__output__
├── uboot.bin -> ../components/aemfvp-a/uboot.bin
__output__
└── uefi.bin -> ../components/aemfvp-a/uefi.bin
```

## Run the software stack
To launch the software stack on the FVP, use a command like the following:

```
FVP_Base_Cortex-A55x4 \
-C pctl.startup=0.0.0.0 \
-C bp.secure_memory=0  \
-C cache_state_modelled=0 \
-C bp.ve_sysregs.mmbSiteDefault=0 \
-C bp.ve_sysregs.exit_on_shutdown=1 \
-C bp.pl011_uart0.untimed_fifos=1 \
-C bp.pl011_uart0.unbuffered_output=1 \
-C bp.pl011_uart0.out_file=<PATH_TO_LOG>/uart0.log \
-C bp.pl011_uart1.untimed_fifos=1 \
-C bp.pl011_uart1.unbuffered_output=1 \
-C bp.pl011_uart1.out_file=<PATH_TO_LOG>/uart1.log \
-C bp.secureflashloader.fname=<SRC_PATH>/output/aemfvp-a/aemfvp-a/tf-bl1.bin \
-C bp.flashloader0.fname=<SRC_PATH>/output/aemfvp-a/aemfvp-a/fip-uboot.bin \
-C bp.virtioblockdevice.image_path=<SRC_PATH>/output/aemfvp-a/components/aemfvp-a/grub-busybox.img \
--data cluster0.cpu0=<SRC_PATH>/output/aemfvp-a/aemfvp-a/Image@0x80080000 \
--data cluster0.cpu0=<SRC_PATH>/output/aemfvp-a/aemfvp-a/fvp-base-revc.dtb@0x83000000
```

This will boot Trusted Firmware-A, UEFI/U-Boot, Linux, and BusyBox in sequence.

## Troubleshoot FVP launch issues
Different FVP models use different CPU instance names.

If you see an error like:
```
Warning: target instance not found: 'FVP_Base_Cortex_A65AEx4_Cortex_A76AEx4.cluster0.cpu0' (data: 'output/aemfvp-a/aemfvp-afvp-base-revc.dtb')
```
Identify the correct instance name for your platform.

Run:
```
FVP_Base_Cortex-A65AEx4+Cortex-A76AEx4 -l | grep RVBARADDR | grep cpu0
```

Example output:
```
cluster0.subcluster1.cpu0.RVBARADDR=0                 # (int   , init-time) default = '0x0'    : Value of RVBAR_ELx register.
```

Update your –data parameters accordingly:
```
--data cluster0.subcluster0.cpu0.thread0=<SRC_PATH>/output/aemfvp-a/aemfvp-a/Image@0x80080000 \
--data cluster0.subcluster0.cpu0.thread0=<SRC_PATH>/output/aemfvp-a/aemfvp-a/fvp-base-revc.dtb@0x83000000
```

> **Tip**  
> Always check the name of the CPU instance when switching between different FVP models.

## Use the GUI (optional)
You can also run the FVP using its graphical user interface:

![View of the FVP GUI](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/linux-on-fvp/fvp.webp)