User Mode and Kernel Mode - Windows drivers
By EliotSeattle
Archived: 2026-04-06 00:29:30 UTC
In this article
1. User mode
2. Kernel mode
3. Related content
A processor in a computer that runs Windows operates in two different modes: user mode and kernel mode. The
processor switches between these modes depending on the type of code it's executing. Applications operate in user
mode. Core operating system components function in kernel mode. Although many drivers operate in kernel
mode, some can function in user mode.
When you launch an application in user mode, Windows creates a process for it. This process provides the
application with a private virtual address space and a private handle table. Since each application's virtual address
space is private, one application can't modify another application's data. Each application runs in isolation. This
approach ensures that if an application crashes, it doesn't affect other applications or the operating system.
The virtual address space of a user-mode application is also limited. A process running in user mode can't access
virtual addresses that are reserved for the operating system. Limiting the virtual address space of a user-mode
application prevents the application from modifying or damaging critical operating system data.
All code that runs in kernel mode shares a single virtual address space. As a result, a kernel-mode driver isn't
isolated from other drivers or the operating system. If a kernel-mode driver mistakenly writes to the wrong virtual
address, it could compromise data that belongs to the operating system or another driver. If a kernel-mode driver
crashes, it causes the entire operating system to crash.
The following diagram illustrates the communication between user-mode and kernel-mode components.
https://docs.microsoft.com/en-us/windows-hardware/drivers/gettingstarted/user-mode-and-kernel-mode
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Last updated on 10/29/2025
Source: https://docs.microsoft.com/en-us/windows-hardware/drivers/gettingstarted/user-mode-and-kernel-mode
https://docs.microsoft.com/en-us/windows-hardware/drivers/gettingstarted/user-mode-and-kernel-mode
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