"Patching the kernel" refers to unsupported modification of the central component or [[Kernel (computer science)|kernel]] of the Windows operating system. Such modification has never been supported by Microsoft because, according to Microsoft, it can greatly reduce system security, reliability, and performance.<ref name="KPP FAQ"/> Although Microsoft does not recommend it, it is technically possible to patch the kernel on [[x86]] editions of Windows; however, with the x64 editions of Windows, Microsoft chose to implement this additional protection and technical barriers to kernel patching.
Since patching the kernel is technically permittedpossible in 32-bit (x86) editions of Windows, several [[antivirus software]] developers use kernel patching to implement antivirus and other security services. ThisThese kind of antivirus softwaretechniques will not work on computers running x64 editions of Windows. Because of this, Kernel Patch Protection hasresulted been criticized for forcingin antivirus makers having to redesign their software without using kernel patching techniques{{citation needed|reason=never met anyone knowledgeable who laments AV writers being unable to patch the windows kernel|date=July 2016}}.
AlsoHowever, because of the design of the Windows kernel, Kernel Patch Protection cannot completely prevent kernel patching.<ref name="skape"/> This has led to additional criticism that since KPP is an imperfect defense, the problems caused to antivirus makersvendors outweigh the benefits because authors of [[malicious software]] will simply find ways around its defenses.<ref name="Samenuk"/><ref name="Gewirtz"/> Nevertheless, Kernel Patching can still prevent problems of system stability, reliability, and performance caused by legitimate software patching the kernel in unsupported ways.
