Fuchsia

The Fuchsia emulator (launched in the Start the emulator section above) is configured to create a virtual device named edu{:.external}, which is an educational device for writing drivers. In the previous section, when the emulator started, Fuchsia’s driver framework detected this edu device in the system, but it wasn’t able to find a driver that could serve the edu device. So the edu device was left unmatched.

In this section, we'll build and publish the qemu_edu{:.external} sample driver (which is a Fuchsia component). Upon detecting a new driver, the driver framework will discover that this new qemu_edu driver is a match for the edu device. Once matched, the qemu_edu driver starts providing the edu device’s services (capabilities) to other components in the system – one of the services provided by the edu device is that it computes a factorial given an integer.

The tasks include:

  • View the drivers that are currently loaded in the emulator instance.
  • Build and publish the qemu_edu driver component.
  • Verify that the qemu_edu driver is loaded to the emulator instance.
  • View detailed information on the qemu_edu component.

In VS Code, do the following:

  1. In the terminal, view the list of the currently loaded drivers:

    tools/ffx driver list --loaded

    This command prints output similar to the following:

    $ tools/ffx driver list --loaded
fuchsia-boot:///#meta/block.core.cm
fuchsia-boot:///#meta/bus-pci.cm
fuchsia-boot:///#meta/display-coordinator.cm
fuchsia-boot:///#meta/fvm.cm
fuchsia-boot:///#meta/goldfish-display.cm
fuchsia-boot:///#meta/goldfish.cm
fuchsia-boot:///#meta/goldfish_address_space.cm
fuchsia-boot:///#meta/goldfish_control.cm
fuchsia-boot:///#meta/goldfish_sensor.cm
fuchsia-boot:///#meta/goldfish_sync.cm
fuchsia-boot:///#meta/hid-input-report.cm
fuchsia-boot:///#meta/hid.cm
fuchsia-boot:///#meta/intel-hda.cm
fuchsia-boot:///#meta/intel-rtc.cm
fuchsia-boot:///#meta/netdevice-migration.cm
fuchsia-boot:///#meta/network-device.cm
fuchsia-boot:///#meta/pc-ps2.cm
fuchsia-boot:///#meta/platform-bus-x86.cm
fuchsia-boot:///#meta/platform-bus.cm
fuchsia-boot:///#meta/qemu-audio-codec.cm
fuchsia-boot:///#meta/ramdisk.cm
fuchsia-boot:///#meta/sysmem.cm
fuchsia-boot:///#meta/virtio_block.cm
fuchsia-boot:///#meta/virtio_ethernet.cm
fuchsia-boot:///#meta/virtio_input.cm
fuchsia-pkg://fuchsia.com/virtual_audio#meta/virtual_audio_driver.cm
fuchsia-boot:///#meta/ahci.cm

  2. Build and publish the qemu_edu driver component:

    tools/bazel run //src/qemu_edu/drivers:pkg.component

    This command prints output similar to the following:

    $ tools/bazel run //src/qemu_edu/drivers:pkg.component
...
INFO: Build completed successfully, 1045 total actions
Running workflow: pkg.component_base
Running task: pkg.debug_symbols_base (step 1/2)
Running task: pkg.component.run_base (step 2/2)
added repository bazel.pkg.component.runnable
Registering fuchsia-pkg://bazel.pkg.component.runnable/qemu_edu#meta/qemu_edu.cm
Successfully bound:
Node 'root.sys.platform.pt.PCI0.bus.00_06_0_.pci-00_06.0-fidl', Driver 'fuchsia-pkg://bazel.pkg.component.runnable/qemu_edu#meta/qemu_edu.cm'.

  3. Verify that the qemu_edu driver is now loaded to the Fuchsia emulator instance:

    tools/ffx driver list --loaded

    This command prints output similar to the following:

    $ tools/ffx driver list --loaded
fuchsia-boot:///#meta/bus-pci.cm
fuchsia-boot:///#meta/display-coordinator.cm
fuchsia-boot:///#meta/fvm.cm
fuchsia-boot:///#meta/goldfish-display.cm
fuchsia-boot:///#meta/goldfish.cm
fuchsia-boot:///#meta/goldfish_address_space.cm
fuchsia-boot:///#meta/goldfish_control.cm
fuchsia-boot:///#meta/goldfish_sensor.cm
fuchsia-boot:///#meta/goldfish_sync.cm
fuchsia-boot:///#meta/hid-input-report.cm
fuchsia-boot:///#meta/hid.cm
fuchsia-boot:///#meta/intel-hda.cm
fuchsia-boot:///#meta/intel-rtc.cm
fuchsia-boot:///#meta/netdevice-migration.cm
fuchsia-boot:///#meta/network-device.cm
fuchsia-boot:///#meta/pc-ps2.cm
fuchsia-boot:///#meta/platform-bus-x86.cm
fuchsia-boot:///#meta/platform-bus.cm
fuchsia-boot:///#meta/qemu-audio-codec.cm
fuchsia-boot:///#meta/ramdisk.cm
fuchsia-boot:///#meta/sysmem.cm
fuchsia-boot:///#meta/virtio_block.cm
fuchsia-boot:///#meta/virtio_ethernet.cm
fuchsia-boot:///#meta/virtio_input.cm
fuchsia-pkg://fuchsia.com/virtual_audio#meta/virtual_audio_driver.cm
{{ '<strong>' }}fuchsia-pkg://bazel.pkg.component/qemu_edu#meta/qemu_edu.cm{{ '</strong>' }}
fuchsia-boot:///#meta/ahci.cm
fuchsia-boot:///#meta/block.core.cm

    Notice that the qemu_edu driver is shown in the loaded drivers list.

  4. View the qemu_edu component information:

    tools/ffx component show qemu_edu.cm

    This command prints output similar to the following:

    $ tools/ffx component show qemu_edu.cm
               Moniker:  /bootstrap/full-pkg-drivers:root.sys.platform.pt.PCI0.bus.00_06_0_.pci-00_06.0-fidl
                   URL:  fuchsia-pkg://bazel.pkg.component/qemu_edu#meta/qemu_edu.cm
           Instance ID:  None
                  Type:  CML Component
       Component State:  Resolved
 Incoming Capabilities:  /svc/fuchsia.driver.compat.Service
                         /svc/fuchsia.logger.LogSink
  Exposed Capabilities:  examples.qemuedu.Service
           Merkle root:  ca337aa579388a7335c8fa53e47ba111b6a58c0b9af7519731e9942dec31f7ef
       Execution State:  Running
          Start reason:  Instance is in a single_run collection
 Outgoing Capabilities:  examples.qemuedu.Service

  5. Click the FUCHSIA LOGS tab on the VS Code panel.

    This panel streams the device logs of the Fuchsia emulator instance.

  6. To fit the messages on the panel, click the Wrap logs icon at the top right corner of the FUCHSIA LOGS panel.

    Fuchsia logs{: .screenshot width=“200”}

  7. In the Filter logs text box, type qemu-edu and press Enter.

    Fuchsia logs{: .screenshot}

    The FUCHSIA LOGS panel now filters logs for the qemu_edu driver only.

    Note: For more information on filtering syntax, see Filter Fuchsia logs.