Pmode stack help!

[beyondsociety]

How would I setup a stack in protected mode. What size should it be and how does it work.

This is how I have set up the segment registers in pmode and I need your help with creating the stack:

mov eax,0x10
mov ds,eax
mov es,eax
mov fs,eax
mov gs,eax

jmp $

[Tim]

mov esp, stack_top
...
[section .bss]
stack: resb 4096
stack_top:

[beyondsociety]

Do I have to set up the stack like you would in the beginning of the bootsector but without disabling and enabling the interrupts?

If I wanted to, could I?

[PlayOS]

When I create my stack I just do this

mov ax, 0x10 ; My Data Segment
mov ss, ax
mov esp, 0x2000000 ; Start at 32MB

I do this for now while I am still learning stuff. You should probably have a descriptor in the GDT just for your stack, but I dont worry about this at the moment.

[Warmaster199]

There is an error. You should base the stack right below the 1MByte mark(Recommendation). What if someone runs your OS on a 486 or a PC without 32MBytes of RAM(some pentiums)? The stack would fail to init... Just a suggestion...

[Pype.Clicker]

I do this for now while I am still learning stuff. You should probably have a descriptor in the GDT just for your stack, but I dont worry about this at the moment.

Watch out: there is a trap about kernel stacks having their own (limitated) segments descriptors: okay, it will help you to avoid auwful kernel stack overflow, but in case of such an overflow, it will raise an exception (stack fault) that can't be handled by a "regular" trap handler (because there's no space on the stack to create the exception stackframe).

So you'll have to setup a "big brother" TSS that will catch at least the stack fault exception on a clean empty stack and resume the situation gracefully