tree: 4e0f0b1b772e3b86b51a6c0412491d0ef84f87e7 [path history] [tgz]
  2. crash-device-info.json
  3. crash-device.bind
  5. isolated-devmgr-tests.cmx
  7. isolated_devmgr.gni
  8. isolated_devmgr.h
  11. OWNERS
  13. test-device-info.json
  14. test-device.bind
  17. usb-virtual-bus-helper.h
  19. usb-virtual-bus.h

Isolated Devmgr

This library contains a set of tools to streamline the creation of components that expose isolated devmgrs.


To create your own version of an isolated devmgr, you first need to define a build rule for it, which will look like:


isolated_devmgr_component("my-devmgr") {
  args = [

  deps = [

The args parameter configures its behavior for your own use case. You can see all the supported arguments here. The main arguments you typically will provide are svc_name and load_driver. svc_name configures the name of the devfs namespace that will be exposed to the component's directory request and load_driver (which can be expressed multiple times) lists drivers to load when it is launched. device_vid_pid_did is optional argument which can be used to create a device.

With this custom isolated devmgr, you can then use it in test cases by either launching it manually using the fuchsia-url for your package (in this example fuchsia-pkg:// or you can inject it as a service and use service injection in your test component's manifest, like so:

    "facets": {
      "fuchsia.test": {
       "injected-services" : {
         "fuchsia.example.MyDevmgr": "fuchsia-pkg://"
    "program": {
        "binary": "test/my_devmgr_test"
    "sandbox": {
        "services": [

In either case you will want to make sure to list the isolated devmgr as a dep for your test component.

Using inspect with isolated devmgr

The device tree and the diagnostics are hosted in the outgoing directory of the test component. In order to view the inspect files -

  1. Add a breakpoint to the test using zxdb.
  2. When breakpoint is hit, open fx shell and find the hub path to the test component. E.g:
find /hub -name fs-management-devmgr.cmx
  1. You can view the inspect file using iquery. E.g:
fx iquery show-file /hub/r/test_env_af569d6f/31969/c/fs-management-devmgr.cmx/32468/out/dev/diagnostics/driver_manager/dm.inspect