The GDT

[karim]

The idea of the GDT is that I define the address of the code, where it starts, like from address X to Y, and the data has a size from this to that, and the stack has a size from this to that, so I can enter Protected Mode. All of this is set up just for the code, data, and stack, so when the Kernel executes, it determines the size of all these based on the Kernel’s own size. In other words, I allocate fixed parts of the RAM for the Kernel, which is the operating system. Is my understanding correct?

[Octocontrabass]

I see you asked this question elsewhere.

Is my understanding correct?

Yes and no. Yes, you understand how segmentation works. No, modern OSes don't use segmentation for memory management, they use paging instead.