OSDev.org

Code: Select all

void kmain(void* mmap_address, uint32_t mmapentrycount, uint32_t memSize)

Code: Select all

mov eax, [memSize]
push eax
movzx eax, word [mmap_entries]
push eax
mov eax, MemMapAddress ;MemMapAddress is a defined constant
push eax
call kmain

Code: Select all

void kmain(void* mmap_address, uint32_t mmapentrycount, uint32_t memSize)
{
	SetColour(0x1F);
	ClearScreen();
	PrintString("Skux OS\n");
	SetupInterrupts();
	timer_install();
	keyboard_install();
	__asm__ __volatile__("sti");
	
	//initialise physical memory manager
	PrintNumberBase16(memSize >> 24);
	PrintNumberBase16(memSize >> 16 & 0xFF);
	PrintNumberBase16(memSize >> 8 & 0xFF);
	PrintNumberBase16(memSize & 0xFF);
	
	
	
	
	//Process memory map
	SMAP_entry* sm = (SMAP_entry*)mmap_address;
	for(unsigned int i=0;i<mmapentrycount;i++)
	{
		if(sm[i].Type == 1 || sm[i].Type == 3) //Free for use or ACPI reclaimable
		{
			//init region
		}
	}
	
	
	
	for(;;)
	{
		__asm__ __volatile__("hlt");
	}
}

Code: Select all

	.file	"kernel.c"
	.section	.rodata
.LC0:
	.string	"Skux OS\n"
	.text
	.globl	kmain
	.type	kmain, @function
kmain:
.LFB0:
	.cfi_startproc
	pushl	%ebp
	.cfi_def_cfa_offset 8
	.cfi_offset 5, -8
	movl	%esp, %ebp
	.cfi_def_cfa_register 5
	subl	$40, %esp
	movl	$31, (%esp)
	call	SetColour
	call	ClearScreen
	movl	$.LC0, (%esp)
	call	PrintString
	call	SetupInterrupts
	call	timer_install
	call	keyboard_install
#APP
# 14 "kernel.c" 1
	sti
# 0 "" 2
#NO_APP
	movl	16(%ebp), %eax
	shrl	$24, %eax
	movzbl	%al, %eax
	movl	%eax, (%esp)
	call	PrintNumberBase16
	movl	16(%ebp), %eax
	shrl	$16, %eax
	movzbl	%al, %eax
	movl	%eax, (%esp)
	call	PrintNumberBase16
	movl	16(%ebp), %eax
	shrl	$8, %eax
	movzbl	%al, %eax
	movl	%eax, (%esp)
	call	PrintNumberBase16
	movl	16(%ebp), %eax
	movzbl	%al, %eax
	movl	%eax, (%esp)
	call	PrintNumberBase16
	movl	8(%ebp), %eax
	movl	%eax, -16(%ebp)
	movl	$0, -12(%ebp)
	jmp	.L2
.L4:
	movl	-12(%ebp), %edx
	movl	%edx, %eax
	addl	%eax, %eax
	addl	%edx, %eax
	sall	$3, %eax
	movl	%eax, %edx
	movl	-16(%ebp), %eax
	addl	%edx, %eax
	movzwl	16(%eax), %eax
	cmpw	$1, %ax
	je	.L3
	movl	-12(%ebp), %edx
	movl	%edx, %eax
	addl	%eax, %eax
	addl	%edx, %eax
	sall	$3, %eax
.L3:
	addl	$1, -12(%ebp)
.L2:
	movl	-12(%ebp), %eax
	cmpl	12(%ebp), %eax
	jb	.L4
.L5:
#APP
# 39 "kernel.c" 1
	hlt
# 0 "" 2
#NO_APP
	jmp	.L5
	.cfi_endproc
.LFE0:
	.size	kmain, .-kmain
	.ident	"GCC: (Ubuntu/Linaro 4.7.2-2ubuntu1) 4.7.2"
	.section	.note.GNU-stack,"",@progbits

Code: Select all

gcc -o kernel.o -c kernel.c -Wall -Wextra -nostdlib -nostartfiles -nodefaultlibs -fno-builtin -std=c99

Code: Select all

andl	$-16, %esp
subl	$16, %esp
movl	$3, 8(%esp)
movl	$2, 4(%esp)
movl	$1, (%esp)
call	kmain

Code: Select all

and esp, -16                                 ;if esp was 0x1234, that would make it 0x1230
sub esp, 16                                  ;and that would make it 0x1220 - rounded down to a 16 byte boundary
mov dwrord ptr [esp + 8], 3
mov dword ptr [esp + 4], 2
mov dword ptr [esp], 1

Code: Select all

and esp, -16
sub esp, 4                                  ;that is probably the bit which is causing the problems.
mov eax, 3
push eax
mov eax, 2
push eax
mov eax, 1
push eax