Driver load time

Otherwise, the driver thread might be starved for processor time by unrelated threads, and startup will be delayed. During a warm startup from standby or hibernation, a functional device driver should complete an S0 set-power IRP immediately, and then request a D0 set-power IRP.

If your driver promptly completes the S0 set-power IRP, the operating system can finish startup while your driver reinitializes the device as a background task. A device driver should not hold a spin lock for more than a brief time, especially during a cold startup from a power-off state.

Otherwise, other device initializations cannot occur in parallel. Fast Startup from a Low-Power State. Skip to main content. This browser is no longer supported. Improve this answer. Sign up or log in Sign up using Google. Sign up using Facebook.

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Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Related Hot Network Questions. Question feed. The only driver load orderings that PnP drivers should depend on are as follows:. The drivers for a child device can depend on the fact that the drivers for the parent device are loaded. However, be aware that a driver in the device stack cannot depend on being loaded sequentially after a device's lower drivers, because the driver might are loaded previously when another device was configured.

Filter drivers in a filter group cannot predict their load ordering. For example, if a device has three registered upper-filter drivers, those three drivers will all be loaded after the function driver but could be loaded in any order within their upper-filter group.

A driver for a child device can depend on the drivers for the parent device being loaded before the child drivers are loaded.

These drivers are in memory when the kernel gets control. Boot-start drivers are loaded before most of the devices are configured, so their load order cannot be determined by device hierarchy. The operating system ignores INF Dependencies entries for boot-start drivers. If a boot device has child devices, those devices are enumerated. The child devices are configured and started if their drivers are also boot-start drivers.

If a device's drivers are not all boot-start drivers, the PnP manager creates a device node devnode for the device but does not start the device yet. After all the boot drivers have loaded and the boot devices are started, the PnP manager configures the rest of the PnP devices and loads their drivers. The PnP manager walks the device tree and loads the drivers for the devnodes that are not yet started that is, any nonstarted devnodes from the previous step.

As each device starts, the PnP manager enumerates the children of the device, if any.