In UEFI,how to prevent me from overwriting the page table?

[wishedtobe]

I was trying to find out where the page table and gdt is in UEFI.Then I found that gdt is located in RT_data,while page table is located in BS_data.It is easy to prevent my OS from overwriting gdt,but how can I deal with the page table?It is said that BS_data would be reclaimed after exiting boot services,and can I reclaim the RT_data?

[Octocontrabass]

It is easy to prevent my OS from overwriting gdt,but how can I deal with the page table?

You need to create your own GDT and page tables. You can't reuse the ones set up by UEFI.

It is said that BS_data would be reclaimed after exiting boot services,and can I reclaim the RT_data?

No, you can't reclaim memory containing runtime data.

[wishedtobe]

It is easy to prevent my OS from overwriting gdt,but how can I deal with the page table?

You need to create your own GDT and page tables. You can't reuse the ones set up by UEFI.

It is said that BS_data would be reclaimed after exiting boot services,and can I reclaim the RT_data?

No, you can't reclaim memory containing runtime data.

Due to the dirty memory space, I can hardly use any part of the memory (overwriting the page table may cause serious problems), making me unable to create my own page tables.

[Octocontrabass]

Why not create your page tables before you reclaim the boot services data?

[wishedtobe]

Why not create your page tables before you reclaim the boot services data?

Maybe you are right.Then what will it be if I overwrite the runtime services?

[Octocontrabass]

Probably something bad will happen, but you shouldn't do it because the UEFI spec says you're not allowed to do it.