OSDev.org

Posted: **Tue Jul 27, 2021 9:00 pm**

Reading this page:
https://wiki.osdev.org/Bare_Bones

I noticed this code snippet setting the stack pointer:

.section .bss
.align 16
stack_bottom:
.skip 16384 # 16 KiB
stack_top:
...
...

As this gets compiled and linked, `stack_bottom` will get a lower memory address than `stack_top`, i.e it will look like this:

Code: Select all

  Low address                                                             High address
[.......... stack_bottom ............... <-- 16 KiB -- > ......... stack_top.........]

The stack point will point to stack_top and grow toward stack_bottom.

But looking at memory layout of C programs, "bottom" should be at the high address and "top" at a lower address:
https://media.cheggcdn.com/media%2Fa00% ... plvboo.png

Shouldn't the labels be reversed in the assembly code?

Posted: **Tue Jul 27, 2021 11:33 pm**

The Wiki is correct.

Posted: **Wed Jul 28, 2021 12:13 am**

The use of "bottom" and "top" in combination with "growing down" can be ambiguous - who's to say the bottom of a stack that grows down isn't the downward side of it?
As long as you point the stack pointer at the correct end, the names aren't too important...

OSDev.org

Is the top and bottom of the stack defined backwards here?

Is the top and bottom of the stack defined backwards here?

Re: Is the top and bottom of the stack defined backwards her

Re: Is the top and bottom of the stack defined backwards her