Ntoskrnl.exe

ntoskrnl.exe (short for Windows NT operating system kernel executable), also known as the kernel image, contains the kernel and executive layers of the Microsoft Windows NT kernel, and is responsible for hardware abstraction, process handling, and memory management. In addition to the kernel and executive mentioned earlier, it contains the cache manager, security reference monitor, memory manager, scheduler (Dispatcher), and blue screen of death (the prose and portions of the code). x86 versions of ntoskrnl.exe depend on bootvid.dll, hal.dll and kdcom.dll (x64 variants of ntoskrnl.exe have these dlls embed into the kernel to increase performance). However, it is not a native application. In other words, it is not linked against . Instead, ntoskrnl.exe containing a standard "start" entry point that calls the architecture-independent kernel initialization function. Because it requires a static copy of the C Runtime objects, the executable is usually about 10 MB in size. In Windows XP and earlier, the Windows installation source ships four kernel image files to support uniprocessor systems, symmetric multiprocessor (SMP) systems, CPUs with PAE, and CPUs without PAE. Windows setup decides whether the system is uniprocessor or multiprocessor, then, installs both the PAE and non-PAE variants of the kernel image for the decided kind. On a multiprocessor system, Setup installs ntkrnlmp.exe and ntkrpamp.exe but renames them to ntoskrnl.exe and ntkrnlpa.exe respectively. Starting with Windows Vista, Microsoft began unifying the kernel images as multi-core CPUs took to the market and PAE became mandatory. Routines in ntoskrnl use prefixes on their names to indicate in which component of ntoskrnl they are defined. Since not all functions are being exported by the kernel, function prefixes ending in i or p (such as Mi, Obp, Iop) are internal and not supposed to be accessed by the user. These functions contain the core code and implements important checks, such as for vulnerabilities, missing arguments and exception handling.