OSDev.org

moondeck wrote:I dont really understand how memory is allocated after i load my kernel. Say, when i define a variable in my kernels C code, where in memory does it go?

Muazzam wrote:Can't we port the drivers from other OS or even reverse engineer it?

embryo2 wrote:

moondeck wrote: But next I see you are talking about your kernel. And one of the responsibilities of a kernel developer is the memory management. It seems you are relying the job on the compiler instead of thinking about your own memory manager. And the consequence is crying with your own question - leaving something unanswered makes you feel lost with the very simple problems.

Muazzam wrote:Wi-Fi is one of the least discussed OS development topics. Has anyone here done it? I guess not. So why not?

• a working kernel, memory management and all;
• a working network stack.

Can't we port the drivers from other OS or even reverse engineer it?

moondeck wrote:I dont really understand how memory is allocated after i load my kernel. Say, when i define a variable in my kernels C code, where in memory does it go?
EDIT: Is it in the kernel? say, i call my kmain() from assembly, which is in the .data section of my linker file. Does the C variable reside there? Its not space limited in any way, other than that its its 4K aligned (because i have aligned it). What about variables in assembly? When i defined a GDT, like this ...
How do i know WHERE it actually points to?

.global x
x: .long 1
.global asm_function
asm_function:
  mov eax, -1
  ret
other_asm_function:
  mov eax, [C_variable]
  mov [x], eax
  push eax
  call other_C_function
  ret

extern int x; /* tell linker that the variable is external */
int asm_function(void); /* protoype the asm function */
int C_variable; /* global variable */
int C_function(void){
  if (x){ /* access the asm variable */
    return asm_function; /* invoke the asm function */
  }
}
int other_C_function(int var){
  return 2 * var;
}

int (*function)(int) = (void *)0x100000;
  function(0);

#define function ((int(*)(int)) ((void *)(*(unsigned long *)0x10000)))
  function(0);

embryo2 wrote:

Muazzam wrote:Can't we port the drivers from other OS or even reverse engineer it?

Yes we can. Can you start working on it to help the community? What stops you?

variables are on the stack unless you have claimed some memory explicitly using something like malloc() or new in C++.

Muazzam wrote:What stops me, to be honest, is my experience.
...
Maybe, my hobby OS would become famous if managed to write a driver for Wi-Fi?

Roman wrote:

variables are on the stack unless you have claimed some memory explicitly using something like malloc() or new in C++.

This is not always true. Global variables reside in statically allocated sections.

Muazzam wrote:Also, my OS is in assembly without POSIX standards.