Making 4kb higher half kernel

[4nt01]

I want to make an higher halv kernel with 4kb pages instead of MB ones. Can you help me? I don't especially understand the part where BootPageDirectory is filled...

[glauxosdever]

Hi,


Could you please link to the guide you are following?

However, I'd suggest you read the theory behind paging first.


Regards,
glauxosdever

[4nt01]

Oh sorry, sure https://wiki.osdev.org/Higher_Half_x86_Bare_Bones I've read theory but to actually code it I didn't have any idea so it helped me

[flerovium]

Usually the page tables you setup in your pre-main initialization routine is just a preliminary mapping.
You will want to setup a proper mapping later anyways and you can use 4KiB pages to map your kernel if you want.
Also using 2MiB pages does not exclude using 4KiB pages for other things.

[4nt01]

Oh man, didn't understand that! Now I have only one question. When does I have to create a new page directory or a new page directory and where should I put those?

[flerovium]

It largely depends on how you plan to structure your memory management...
You propably want a way to allocate physical pages before setting up your new tables.
You can then use a recursive mapping to access the allocated tables (PD, PT) in virtual memory.