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Linux

Overview

A simple starter software stack to boot to a Linux command prompt via a basic bootloader on the Armv8-R AEM FVP model.

The platform software is provided via a Yocto package which contains all the instructions necessary to fetch and build the source as well as where to download the model and launch the example.

Fixed Virtual Platforms (FVP) are complete simulations of an Arm system, including processor, memory and peripherals. These are set out in a "programmer's view", which gives you a comprehensive model on which to build and test your software.

The Armv8-R AEM FVP is a free of charge Armv8-R Fixed Virtual Platform. It supports the latest Armv8-R feature set.

This BSP implements a reference stack for the AArch64 support in the R-class, first announced with the Cortex-R82 processor. 

The Fast Models Fixed Virtual Platforms (FVP) Reference Guide can be found here.

BSP Support

The Armv8-R AEM FVP Yocto MACHINE supports the following BSP components on the Yocto hardknott release branch, where a standard Linux kernel can be built and run (instructions below):

  • boot-wrapper-aarch64 
  • Linux kernel: linux-yocto-5.10

Quick start: How to Build and Run

Host environment setup

The following instructions have been tested on hosts running Ubuntu 18.04 and Ubuntu 20.04. 

Install the required packages for the build host:

https://docs.yoctoproject.org/3.3.1/singleindex.html#required-packages-for-the-build-host

Install the kas setup tool for bitbake based projects:

$ pip3 install --user kas

For more details on kas, see https://kas.readthedocs.io/

Note: The host machine should have at least 50 GBytes of free disk space for the next steps to work correctly.

Fetch sources

Fetch the meta-arm repository into a build directory:

$ mkdir -p ~/fvp-baser-aemv8r64-build
$ cd ~/fvp-baser-aemv8r64-build
$ git clone –-branch hardknott https://git.yoctoproject.org/git/meta-arm

Build

Building with the standard Linux kernel:

$ cd ~/fvp-baser-aemv8r64-build
$ kas build meta-arm/kas/fvp-baser-aemv8r64-bsp.yml

Networking

To enable networking on the FVP via a host network interface, you will need to install the following package(s):

Ubuntu 18.04:

$ sudo apt-get install libvirt-bin

Ubuntu 20.04:

$ sudo apt-get install libvirt-dev libvirt-daemon qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils

Once that is installed for your OS version, setup tap0 using the following commands:

$ sudo virsh net-start default
$ sudo ip tuntap add dev tap0 mode tap user $(whoami)
$ sudo ifconfig tap0 0.0.0.0 promisc up
$ sudo brctl addif virbr0 tap0

To clean up the tap0 interface on the host use the following commands:

$ sudo brctl delif virbr0 tap0
$ sudo ip link set virbr0 down
$ sudo brctl delbr virbr0
$ sudo virsh net-destroy default
$ sudo ip link delete tap0

Run

To Run the Fixed Virtual Platform simulation tool you must download "Armv8-R AEM FVP" from Arm developer (this might require the user to register) from this address:

https://developer.arm.com/tools-and-software/simulation-models/fixed-virtual-platforms/arm-ecosystem-models

and install it on your host PC.

To run an image after the build is done:

$ export YOCTO_DEPLOY_IMGS_DIR="~/fvp-baser-aemv8r64-bsp/build/tmp/deploy/images/fvp-baser-aemv8r64/"
$ cd <path-to-AEMv8R_base_pkg>/models/Linux64_GCC-6.4/
$ ./FVP_BaseR_AEMv8R \
     -C bp.dram_metadata.init_value=0 \
     -C bp.dram_metadata.is_enabled=true \
     -C bp.dram_size=8 \
     -C bp.exclusive_monitor.monitor_access_level=1 \
     -C bp.pl011_uart0.unbuffered_output=1 \
     -C bp.pl011_uart0.untimed_fifos=true \
     -C bp.refcounter.non_arch_start_at_default=1 \
     -C bp.smsc_91c111.enabled=0 \
     -C bp.ve_sysregs.mmbSiteDefault=0 \
     -C cache_state_modelled=true \
     -C cluster0.gicv3.cpuintf-mmap-access-level=2 \
     -C cluster0.gicv3.SRE-enable-action-on-mmap=2 \
     -C cluster0.gicv3.SRE-EL2-enable-RAO=1 \
     -C cluster0.gicv3.extended-interrupt-range-support=1 \
     -C cluster0.has_aarch64=1 \
     -C cluster0.NUM_CORES=4 \
     -C cluster0.stage12_tlb_size=512 \
     -C gic_distributor.GICD_CTLR-DS-1-means-secure-only=1 \
     -C gic_distributor.GITS_BASER0-type=1 \
     -C gic_distributor.ITS-count=1 \
     -C gic_distributor.ITS-hardware-collection-count=1 \
     -C gic_distributor.has-two-security-states=0 \
     -C pctl.startup=0.0.0.* \
     -C bp.virtio_net.enabled=1 \
     -C cache_state_modelled=0 \
     -C bp.vis.rate_limit-enable=0 \
     -C bp.virtio_net.hostbridge.interfaceName=tap0 \
     -a cluster0*=${YOCTO_DEPLOY_IMGS_DIR}/linux-system.axf \
     -C bp.virtioblockdevice.image_path=${YOCTO_DEPLOY_IMGS_DIR}/core-image-minimal-fvp-baser-aemv8r64.wic

Note: The terminal console login is `root` without password.

Devices supported in the kernel

  • serial
  • virtio disk
  • virtio network
  • watchdog
  • rtc

Devices not supported or not functional

  • Only one CPU since SMP is not functional in boot-wrapper-aarch64 yet.