KERNEL LOADER SOFTWARE STARTED BY

Kernel Loader Software Started By

A separate boot loader or. In the case of UEFI, the kernel itself can be directly launched by the UEFI using the EFI boot stub. It is responsible for loading the kernel with the wanted kernel parameters, and initial RAM disk based on configuration files. A boot loader is a piece of software started by the firmware (BIOS or UEFI).

New and Improved V3.0 Installing and starting NT kernel mode drivers can be a hassle. The PnP manager loads the drivers for each device as the device is configured, if the drivers were not previously loaded for another device.Driver Loader. Windows and the PnP manager configure devices starting with the system root device, and then they configure the child devices of the root device (for example, a PCI adapter), the children of those devices, and so on.

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.A driver in the device stack can depend on the fact that any drivers below it are loaded.For example, the function driver can be certain that any lower-filter drivers 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. Conversely, a driver should be able to be unloaded any time that the PnP manager determines that there are no longer devices present that the driver services. PnP drivers must not set this start type.A PnP driver should be written so that it can be loaded when Windows configures a device that the driver services. If a driver services both PnP and non-PnP devices, it should set this start type.Non-PnP driver that must be started by the service control managerSuch a driver should have the start type SERVICE_AUTO_START (0x02).

The child devices are configured and started if their drivers are also boot-start drivers. (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.The PnP manager calls the DriverEntry routines of the SERVICE_BOOT_START drivers so the drivers can service the boot devices.If a boot device has child devices, those devices are enumerated. These drivers are in memory when the kernel gets control.Boot-start drivers can use INF LoadOrderGroup entries to order their loading. A driver for a child device can depend on the drivers for the parent device being loaded before the child drivers are loaded.To reinforce the importance of setting the correct StartType value, the following list describes how Windows and the PnP manager use the StartType entries in INF files:On system startup, the operating system loader loads drivers of type SERVICE_BOOT_START before it transfers control to the kernel.

The PnP manager processes registry entries that are the result of INF LoadOrderGroup entries for these drivers. (The descendants might or might not be PnP-enumerable.)The PnP manager loads drivers of StartType SERVICE_SYSTEM_START that are not yet loaded.These drivers detect and report their non-PnP devices. The load ordering is based on the physical device hierarchy.At the end of this step, all the devices are configured, except devices that are not PnP-enumerable and the descendants of those devices. Many of these drivers are SERVICE_DEMAND_START drivers.The PnP manager ignores registry entries that were created as a result of INF Dependencies entries and LoadOrderGroup entries for drivers that it loads in this step. As each device starts, the PnP manager enumerates the children of the device, if any.As it configures these devices, the PnP manager loads the drivers for the devices, regardless of the drivers' StartType values (except when StartType is SERVICE_DISABLED) before proceeding to start the devices.

If a driver should be promoted on booting from a VHD, specify 0x2 (CM_SERVICE_VIRTUAL_DISK_BOOT_LOAD) If a driver should be promoted to be a boot start driver on network boot, specify 0x1 (CM_SERVICE_NETWORK_BOOT_LOAD). You can specify one or more (ORed) of the following numeric values in the INF file, expressed as a hexadecimal value: The service control manager ignores INF LoadOrderGroup information.See the Microsoft Windows SDK documentation for more information about the service control manager.Using BootFlags to Promote a Driver's StartType at Boot Depending on Boot ScenarioThe operating system can promote a driver's StartType to be a boot start driver depending on the BootFlags value specified in the driver's INF. Be aware that the Dependencies information is only processed for non-PnP drivers because any necessary PnP drivers were loaded in an earlier step of system startup. This information is from Dependencies entries in INF AddService entries.

If a driver should be promoted on WinPE boot, specify 0x80 (CM_SERVICE_WINPE_BOOT_LOAD).For more information about promoting a driver's StartType at boot, depending on the boot scenario, see INF AddService directive.

Kernel Driver Loader