Nt kernel

The types of drivers may be divided into two categories: User mode drivers and Kernel mode drivers.User mode drivers ofen provide a subsystem-specific interface to a standard Kernel mode driver. In the Win32 Environment Subsystem, User mode drivers are implemented as Dynamic Linked Libraries (DLLs).As an example, most Audio Compression Manager (ACM) drivers, which implement audio compression algorithms, are User mode, sofware-only drivers. On the other hand, Multimedia Control Interface (MCI) drivers are User mode drivers that typically'interact with underlying hardware through the use of a collaborating Kernel mode driver. Kernel mode drivers form part of the Windows NT Executive layer and run in Kernel mode, as their name implies. Kernel mode drivers are accessed and supported by the I/O Manager.The four types of Kernel mode drivers are as follows:File System driversIntermediate driversDevice driversMini-drivers. File System drivers exist at the top of the NT Kernel mode driver stack. File System drivers play a special role in Windows NT because they are tightly coupled with the NT Memory and Cache Manager subsystems.File System drivers may implement a physical fle system, such as NTFS or FAT; however, they may also implement a distributed or networked facility.Intermediate drivers form the middle layer of the NT driver hierarchy, sitting below File System drivers and above Device drivers.Intermediate drivers provide either a "value-added" feature (such as mirroring or disk-level encryption) or class processing for devices. In either case, Intermediate drivers rely upon the Device drivers below them in the NT driver hierarchy for access to

Memory associated with NT's kernel. The components in user mode must call on the kernel if they want to access hardware or allocate physical or logical resources.The kernel executes in a privileged mode: It can directly access memory and hardware. The kernel consists of several Executive subsystems, which are responsible for managing resources, including the Process Manager, the I/O Manager, the Virtual Memory Manager, the Security Reference Monitor, and a microkernel that handles scheduling and interrupts. The system dynamically loads device drivers, which are kernel components that interface NT to different peripheral devices. The hardware abstraction layer (HAL) hides the specific intricacies of an underlying CPU and motherboard from NT. NT's native API is the API that user-mode applications use to speak to the kernel. This native API is mostly undocumented, because applications are supposed to speak Win32, DOS, OS/2, POSIX, or Win16, and these respective OS environments interact with the kernel on the application's behalf.VMS doesn't have different OS personalities, as NT does, but its kernel and Executive subsystems are clear predecessors to NT's. Digital developers wrote the VMS kernel almost entirely in VAX assembly language. To be portable across different CPU architectures, Microsoft developers wrote NT's kernel almost entirely in C. In developing NT, these designers rewrote VMS in C, cleaning up, tuning, tweaking, and adding some new functionality and capabilities as they went. This statement is in danger of trivializing their efforts; after all, the designers built a new API (i.e., Win32), a new file system (i.e., NTFS), and a new graphical interface subsystem and administrative environment while maintaining backward compatibility with DOS, OS/2, POSIX, and Win16. Nevertheless, the migration of VMS internals to NT was so thorough that within a few weeks of NT's release, Digital engineers noticed the striking similarities.Those similarities could fill a book. In fact, you can read sections of VAX/VMS Internals and Data Structures (Digital Press) as an accurate description of NT internals simply by translating VMS terms to NT terms. Table 1 lists a few VMS terms and their NT translations. Although I won't go into detail, I will discuss some of the major similarities and differences between Windows NT 3.1 and VMS 5.0, the last version of VMS Dave Cutler and his team might have influenced. This discussion assumes you have some familiarity with OS concepts (for background information about NT's architecture, see "Windows NT Architecture, Part 1" March 1998 and "Windows NT Architecture, Part 2" April 1998).TABLE 2: Significant VMS and NT SimilaritiesNT's processes are virtually the same as VMS's processes (Table 2, page 118, shows a comparison of VMS and NT processes). In NT, as in VMS, the process scheduler implements 32 priority levels. The process with the highest priority is always running, and processes with equal priority are scheduled in a round-robin pattern. The system considers the 16 high-priority levels realtime or fixed priorities, because the process scheduler doesn't manipulate priority in processes the system assigns to that range. The 16 low-priority levels (except 0, which the

The correct base image is loaded later (this procedure is called “Deferred application”.)The operations that are performed by the engine for applying a patch are described by an array of hotpatch descriptors. A hotpatch descriptor tells the engine what type of patch each record specifies (function patch, global symbol patch, indirect call, CFG call target and so on...). It is composed of a header and one or more hotpatch records. Each record specifies the patch’s parameters that depend on the type of the descriptor, like the source and target function’s RVA, and the original opcodes bytes.The Hotpatch engine is implemented in various parts of the operating system, mostly in the NT and Secure kernel. The engine, as introduced in the previous paragraph, supports different kinds of images: Hypervisor, Secure Kernel and its modules, NT Kernel drivers and User-mode processes. The hotpatch engine requires the Secure Kernel to be running.For applying a patch to an image, the NT kernel takes several steps that start in the MiLoadHotPatch internal function, which temporarily maps the patch image in the system address space and performs the initial analysis with the goal to search and verify the hotpatch information contained in the PE data structures (showed in Figure 1). After the checksum and timestamp of the target image for which the patch has been designed are located, the NT kernel determines whether the corresponding base image is loaded in the system (the base image can also be a secure image, like the Hypervisor or the Secure Kernel, so this step also needs to invoke the secure kernel).When a compatible image is detected, the NT kernel begins to apply the patch to the target base image using a procedure that is a bit different depending on the type of the base image (user-mode library or process, kernel driver or a secure image). In general, the hotpatch engine maps the patch image in the same address space as the base image (as showed in Figure 2): for user-mode patches, the patch image will be mapped in each process that has the base image loaded.Note that the hotpatch engine also supports session drivers. A session driver is a driver that lives in a kernel-mode address space that is tied to the user logon session (note that the session address space is generated by one particular root page table entry, which is switched on demand by the Memory manager depending on the active session). This means that a particular session can have a driver mapped which does not exist in another session. The Hotpatch engine is able to attach to all sessions in the system thanks to the “HotPatch” process created in phase 1 of the NT Kernel initialization. This minimal process has the characteristic to not belong to any session. The hotpatch engine can thus use that process to temporarily attach to any session in the system and perform the patch application only to the sessions where the driver is currently loaded.Figure 2. Various address spaces supported by

New Preview Pane from the left, within a new interface and tool bar customisation, including new changes to the tool bar and the throbber has been also added. Windows 2000 also now makes folders to function inside of Windows Explorer, instead of functioning in a seperate window and introduces new icons.Shell: Windows 2000 has improved a lot the shell, within implementing a new gray faint animation while closing and the new power slider, instead of power checkmarks. The Start Menu has been updated to include new icons and an expanded size of the start menu, too. Gradient tile bars (first implemented in Windows 98) now are also implemented, within the pastel blue color, including the cursor to have shadows, which you can enable int the Control Panel, or disable the shadows. The blue accent color has been also implemented, replacing the teal color saw in earlier 9x OSes and earlier Windows NT OSes. New system icons were implemented, too and new animations were also implemented into the context menu, too.Active Desktop: Active desktop into the context menu has been also changed, which applies the desktop that you got in hands, too with the most activation used. In Windows NT 4.0, you cannot choose an active desktop into the context menu.JavaScript: JavaScript has been implemented for Windows game developers and owners of other games and professional scripters in professional applications. In Windows NT 4.0, this wasn't implemented.Hybrid kernel: The Hybrid kernel has been implemented, instead of the Cairo kernel. In Windows NT 4.0, the Cairo kernel was used instead.New icons and sounds: Windows 2000 implements newer sounds, including changed sounds, log off and log on sounds, though Windows NT 4.0 includes the older sounds and not too many new sounds. The icons of Windows NT 4.0 are different, to match Windows 95 PLUS!, but in Windows 2000, they have changed to unqiue icons, which were also found in Windows Me.NTFS 3.0: NTFS 3.0 was also implemented, which was to meet people around the whole network. In Windows NT 4.0, this wasn't introduced.Encrypting File System: The Encrypting File System has been implemented, which in Windows NT 4.0 it wasn't.The new Accessibility applet into the Control Panel has been implemented. It implemented the new toggle keys option for people which want to change the accessibility of the toggle keys. Like for example, you can make the audio, mono, like just simply muted and not hearing anyone. FilterKeys were also implemented, which you changed the speed of the keys while you type. StickyKeys were also implemented, which toggles new mini sounds made for ir, recycle and ring sounds, including and the new sticky sounds. When you press the shift key 5 times, it will

The SYS C: command (for the C drive) to restore the DOS boot sector. After you restore the DOS boot sector, the system will boot only to DOS. To restore the system's ability to boot to other OSs, you can use the three boot disks that came with NT, or the ERD, to restore the boot sector pointers to ntldr and write the DOS boot sector information to a new bootsect.dos file (which you'll want to back up).Problems with the SCSI Device The file ntbootdd.sys is a device driver only for the SCSI controller. (If you use IDE, you do not need this file.) If the SCSI disk is device 0 or 1, you do not need this file because the BIOS on the SCSI card lets the boot process access the disk. If the disk is another device number, the system does not use the BIOS to boot, and you need a device driver. The file ntbootdd.sys is the device driver for your SCSI card. You can copy this file from another computer with the same SCSI card, or you can copy it from the NT CD-ROM and rename it if you know which file your SCSI card uses.Here Comes the Blue Screen At this point in the NT boot process, the device drivers are loaded (as you watch the dots moving across the top of the screen). Then the screen turns blue, and the NT kernel load process starts. If the kernel files are missing or damaged, you receive the error message that Screen 1 shows. (If you wonder how I captured this screen before the OS loaded, I cheated and re-created the screen.) In this case, the kernel files might be missing (e.g., on a multiple-boot system in which someone booted to DOS and deleted the NT