Platforms describe the system underlying the OS. They encapsulate hardware- and firmware-specific details. In most cases, the generic Platform class, which gets used if a platform is not explicitly specified on Target creation, will be sufficient. It will automatically query as much platform information (such CPU topology, hardware model, etc) if it was not specified explicitly by the user.

class devlib.platform.Platform(name=None, core_names=None, core_clusters=None, big_core=None, model=None, modules=None)
  • name – A user-friendly identifier for the platform.
  • core_names – A list of CPU core names in the order they appear registered with the OS. If they are not specified, they will be queried at run time.
  • core_clusters – A list with cluster ids of each core (starting with 0). If this is not specified, clusters will be inferred from core names (cores with the same name are assumed to be in a cluster).
  • big_core – The name of the big core in a big.LITTLE system. If this is not specified it will be inferred (on systems with exactly two clusters).
  • model – Model name of the hardware system. If this is not specified it will be queried at run time.
  • modules – Modules with additional functionality supported by the platform (e.g. for handling flashing, rebooting, etc). These would be added to the Target’s modules. (See Modules).

Versatile Express

The generic platform may be extended to support hardware- or infrastructure-specific functionality. Platforms exist for ARM VersatileExpress-based Juno and TC2 development boards. In addition to the standard Platform parameters above, these platforms support additional configuration:

class devlib.platform.arm.VersatileExpressPlatform

Normally, this would be instantiated via one of its derived classes (Juno or TC2) that set appropriate defaults for some of the parameters.

  • serial_port – Identifies the serial port (usual a /dev node) on which the device is connected.
  • baudrate – Baud rate for the serial connection. This defaults to 115200 for Juno and 38400 for TC2.
  • vemsd_mount – Mount point for the VEMSD (Versatile Express MicroSD card that is used for board configuration files and firmware images). This defaults to "/media/JUNO" for Juno and "/media/VEMSD" for TC2, though you would most likely need to change this for your setup as it would depend both on the file system label on the MicroSD card, and on how the card was mounted on the host system.
  • hard_reset_method

    Specifies the method for hard-resetting the devices (e.g. if it becomes unresponsive and normal reboot method doesn’t not work). Currently supported methods are:

    dtr:reboot by toggling DTR line on the serial connection (this is enabled via a DIP switch on the board).
    reboottxt:reboot by writing a filed called reboot.txt to the root of the VEMSD mount (this is enabled via board configuration file).

    This defaults to dtr for Juno and reboottxt for TC2.

  • bootloader

    Specifies the bootloader configuration used by the board. The following values are currently supported:

    uefi:Boot via UEFI menu, by selecting the entry specified by uefi_entry parameter. If this entry does not exist, it will be automatically created based on values provided for image, initrd, fdt, and bootargs parameters.
    uefi-shell:Boot by going via the UEFI shell.
    u-boot:Boot using Das U-Boot.
    bootmon:Boot directly via Versatile Express Bootmon using the values provided for image, initrd, fdt, and bootargs parameters.

    This defaults to u-boot for Juno and bootmon for TC2.

  • flash_method – Specifies how the device is flashed. Currently, only "vemsd" method is supported, which flashes by writing firmware images to an appropriate location on the VEMSD.
  • image – Specfies the kernel image name for uefi or bootmon boot.
  • fdt – Specifies the device tree blob for uefi or bootmon boot.
  • initrd – Specifies the ramdisk image for uefi or bootmon boot.
  • bootargs – Specifies the boot arguments that will be pass to the kernel by the bootloader.
  • uefi_entry – Then name of the UEFI entry to be used/created by uefi bootloader.
  • ready_timeout – Timeout, in seconds, for the time it takes the platform to become ready to accept connections. Note: this does not mean that the system is fully booted; just that the services needed to establish a connection (e.g. sshd or adbd) are up.

Gem5 Simulation Platform

By initialising a Gem5SimulationPlatform, devlib will start a gem5 simulation (based upon the arguments the user provided) and then connect to it using Gem5Connection. Using the methods discussed above, some methods of the Target will be altered slightly to better suit gem5.

class devlib.platform.gem5.Gem5SimulationPlatform(name, host_output_dir, gem5_bin, gem5_args, gem5_virtio, gem5_telnet_port=None)

During initialisation the gem5 simulation will be kicked off (based upon the arguments provided by the user) and the telnet port used by the gem5 simulation will be intercepted and stored for use by the Gem5Connection.

  • name – Platform name
  • host_output_dir – Path on the host where the gem5 outputs will be placed (e.g. stats file)
  • gem5_bin – gem5 binary
  • gem5_args – Arguments to be passed onto gem5 such as config file etc.
  • gem5_virtio – Arguments to be passed onto gem5 in terms of the virtIO device used to transfer files between the host and the gem5 simulated system.
  • gem5_telnet_port – Not yet in use as it would be used in future implementations of devlib in which the user could use the platform to pick up an existing and running simulation.

Based upon the OS defined in the Target, the type of Gem5Connection will be set (AndroidGem5Connection or AndroidGem5Connection).


This method provides specific setup procedures for a gem5 simulation. First of all, the m5 binary will be installed on the guest (if it is not present). Secondly, three methods in the Target will be monkey-patched:

  • reboot: this is not supported in gem5
  • reset: this is not supported in gem5
  • capture_screen: gem5 might already have screencaps so the monkey-patched method will first try to transfer the existing screencaps. In case that does not work, it will fall back to the original Target implementation of capture_screen().

Finally, it will call the parent implementation of update_from_target().


The m5 binary be installed, if not yet installed on the gem5 simulated system. It will also resize the gem5 shell, to avoid line wrapping issues.