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0 pointsuseerup11y ago0 comments

NT is a hybrid kernel for sure. In a monolithic kernel everything would be running in ring 0.

NT is a hybrid kernel because some drivers run in ring 0, others (typically peripheral drivers) run outside ring 0. Some drivers (specifically graphics card drivers) run split in kernel mode and user mode: A small part runs in kernel mode, while the complex part runs in user mode.

While you are correct that the graphics driver was moved to kernel mode for Windows 2000/XP, it was actually moved half-way back with Vista. This was in fact the reason why graphics drivers sucked in the beginning for Vista: MS only gave the vendors 4 months since the last change to the graphics driver model before Vista was released.

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lobster_johnson11y ago

It's still running pretty much everything in ring 0 that a traditional monolithic kernel would. All the "complex parts" run in kernel mode.

The new WDDM driver model runs a user-mode driver, but it's still backed by a set of kernel-mode drivers [1], including the "display miniport" driver.

As kernels go, it's pretty monolithic. What makes it more like a microkernel is that many of the internal APIs use a message-passing model rather than direct calls.

[1] https://msdn.microsoft.com/en-us/library/windows/hardware/ff...

the_why_of_y11y ago

On Linux the OpenGL implementation of the graphics driver (which is by far the most complex part) runs in user space, as do drivers for printers and a lot of other USB devices. However that doesn't make Linux a "hybrid kernel", and neither does what you said make NT one.

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