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Release 2 - SMP

BSP Support

The fvp-baser-aemv8r64 Yocto MACHINE supports the following BSP components, where either a standard or Real-Time Linux kernel (PREEMPT_RT) can be built and run:

  • boot-wrapper-aarch64: provides PSCI support
  • Linux kernel: linux-yocto-5.10

  • Linux kernel with PREEMPT_RT support: linux-yocto-rt-5.10

Note that the Real-Time Linux kernel (PREEMPT_RT) does not use the real-time architectural extensions of the Armv8-R feature set.

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/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/

To build the images for fvp-base machine, you also need to:

  • Download the FVP_Base_AEMv8R_11.15_14.tgz  image AEM V8-R FVP Installer (Linux) package from Arm's website. You need to have an account and be logged in to be able to download it.
  • Set absolute path to the FVP_Base_AEMv8R_11.15_14.tgz  downloaded package in FVP_BASE_R_AEM_TARBALL_URI 
  • Accept EULA in FVP_BASE_R_ARM_EULA_ACCEPT 

The variables should be set like so:

$ FVP_BASE_R_AEM_TARBALL_URI="file:///absolute/path/to/FVP_Base_AEMv8R_11.15_14.tgz"
$ FVP_BASE_R_ARM_EULA_ACCEPT="True"

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 https://git.yoctoproject.org/git/meta-arm

Build

Building with the standard Linux kernel:

$ cd ~/fvp-baser-aemv8r64-build
$ export FVP_BASE_R_AEM_TARBALL_URI="file:///absolute/path/to/FVP_Base_AEMv8R_11.15_14.tgz"
$ export FVP_BASE_R_ARM_EULA_ACCEPT="True"
$ kas build meta-arm/kas/fvp-baser-aemv8r64-bsp.yml

Building with the Real-Time Linux kernel (PREEMPT_RT):

$ cd ~/fvp-baser-aemv8r64-build
$ export FVP_BASE_R_AEM_TARBALL_URI="file:///absolute/path/to/FVP_Base_AEMv8R_11.15_14.tgz"
$ export FVP_BASE_R_ARM_EULA_ACCEPT="True"
$ kas build meta-arm/kas/fvp-baser-aemv8r64-rt-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 net-tools

Ubuntu 20.04:

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

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 an image after the build is done with the standard Linux kernel:

$ kas shell --keep-config-unchanged \
   meta-arm/kas/fvp-baser-aemv8r64-bsp.yml \
       --command "../layers/meta-arm/scripts/runfvp \
            --console \
            -- \
                --parameter 'bp.smsc_91c111.enabled=1' \
                --parameter 'bp.virtio_net.hostbridge.interfaceName=tap0'"

To run an image after the build is done with the Real-Time Linux kernel (PREEMPT_RT):

$ kas shell --keep-config-unchanged \
   meta-arm/kas/fvp-baser-aemv8r64-rt-bsp.yml \
       --command "../layers/meta-arm/scripts/runfvp \
            --console \
            -- \
                --parameter 'bp.smsc_91c111.enabled=1' \
                --parameter 'bp.virtio_net.hostbridge.interfaceName=tap0'"

Note: The terminal console login is root without password.

To finish the fvp emulation, you need to close the telnet session and stop the runfvp script:

  • To close the telnet session:
    • Escape to telnet console with ctrl+].
    • Run quit to close the session.
  • To stop the runfvp :
    • Type Ctrl+C  and wait for kas  process to finish.

File sharing between host and fvp

It is possible to share a directory between the host machine and the fvp using the virtio P9 device component included in the kernel. To do so, create a directory to be mounted from the host machine:

$ mkdir /path/to/host-mount-dir

Then, add the following parameter containing the path to the directory when launching the model:

$ --parameter 'bp.virtiop9device.root_path=/path/to/host-mount-dir'

Once you are logged into the fvp, the host directory can be mounted in a directory on the model using the following command:

$ mount -t 9p -o trans=virtio,version=9p2000.L FM /path/to/fvp-mount-dir

Devices supported in the kernel

  • serial
  • virtual 9p
  • virtio disk
  • virtio network
  • watchdog
  • rtc

Know Issues and Limitations

  • Only PSCI CPU_ON and CPU_OFF functions are supported
  • Linux kernel does not support booting from secure EL2 on Armv8-R AArch64
  • Linux KVM does not support Armv8-R AArch64

ChangeLog

  • Enabled SMP support via boot-wrapper-aarch64 providing the PSCI CPU_ON and CPU_OFF functions
  • Introduced Armv8-R64 compiler flags
  • Added Linux PREEMPT_RT support via linux-yocto-rt-5.10
  • Added support for file sharing with the host machine using Virtio P9
  • Added support for runfvp
  • Added performance event support (PMU) in the Linux device tree
  • Introduced the fvp-baser-aemv8r64 machine and its BSP composed of boot-wrapper-aarch64 and linux-yocto-5.10 supporting serial, virtio disk, virtio network, watchdog and rtc