Re-wrote boot code, moved to x86 folder

src/x86/entry.S

@@ -143,181 +143,54 @@ memory_map:
 .global _start
 .type _start, @function
 _start:
+	# This platform reqires a Multiboot2 bootloader.
 	cmp $0x36d76289, %eax
-	jne _err
+	jne .err
 
-	movb $64, 0xB8000
+	# Initialize stack in physical address space
+	mov $stackTop, %esp
+	sub $BASE_DIFF, %esp
 
-	mov $system_info, %edi
-	sub $BASE_DIFF, %edi
-	add $8, %ebx
-	
-switch:	
-	mov (%ebx), %eax
-	cmp $0, %eax
-	je s_end
-	cmp $1, %eax
-	je tag_1
-	cmp $3, %eax
-	je tag_3
-	cmp $4, %eax
-	je tag_4
-	cmp $6, %eax
-	je tag_6
-	cmp $21, %eax
-	je tag_21
-	jmp def
-
-# Boot command line
-tag_1:	
-	mov 4(%ebx), %ecx
-	sub $8, %ecx
-	mov %ebx, %esi
-	add $8, %esi
-	mov $_bootCmdLine, %edi
-	sub $BASE_DIFF, %edi
-	rep movsb
-	mov $system_info, %edi
-	sub $BASE_DIFF, %edi
-	jmp def
-
-tag_3:
-	mov 8(%ebx), %esi
-	mov (%esi), %eax
-	mov %al, (0xB8004)
-	mov %ah, (0xB8006)
-	shr $16, %eax
-	mov %al, (0xB8008)
-	mov %ah, (0xB800a)
-	jmp def
-
-# Basic memory info
-tag_4:	
-	mov 8(%ebx), %eax
-	mov %eax, (%edi)
-	mov 12(%ebx), %eax
-	mov %eax, 4(%edi)
-	jmp def
-
-# Memory map
-tag_6:	
-	mov $memory_map, %esi
-	sub $BASE_DIFF, %esi	# set esi to point to the table in the kernel image
-	mov 4(%ebx), %ecx
-	sub $16, %ecx		# set ecx to store the size of the table provided by the bootloader
-	mov 8(%ebx), %edx	# set edx to store the size of each table entry
-	add $16, %ebx		# move ebx up to the first entry
-1:	mov (%ebx), %eax
-	mov %eax, (%esi)	# save the address of that region in memory
-	mov 8(%ebx), %eax	
-	mov %eax, 4(%esi)	# save the size of that region in memory
-	mov 16(%ebx), %eax
-	mov %eax, 8(%esi)	# save the type of memory in that region
-	add $12, %esi		# move esi to the next entry in the kernel's array
-	add %edx, %ebx		# move ebx to the next entry in the bootloader's array
-	sub %edx, %ecx		# subtract the size of an entry from ecx.
-	jnz 1b			# loop if there are entries left
-	mov $0, %eax
-	mov %eax, (%esi)
-	mov %eax, 4(%esi)
-	mov %eax, 8(%esi)
-	jmp switch
-	
-# Program image location
-tag_21:	
-	mov 8(%ebx), %eax
-	mov %eax, 8(%edi)
-	jmp def
-	
-def:	
-	mov 4(%ebx), %eax
-	add $7, %eax
-	and $0xFFFFFFF8, %eax
-	add %eax, %ebx
-	jmp switch
-s_end:	
-
-	movb $64, 0xB8002
-	
-	mov $0, %ecx
-1:
-	# Generate a page table entry pointing to a page in the kernel binary
-	mov %ecx, %eax
-	mov $4096, %edx
-	mul %edx
-	or $3, %eax
-
-	# Load the address of the temporary page table and translate it to a physical address
-	mov $_tempPgTable, %edi
-	sub $BASE_DIFF, %edi
-
-	# Save the PTE into an entry in the temporary page table
-	mov %eax, (%edi, %ecx, 4)
-
-	# Load the address of the identity map and translate it to a physical address
-	mov $_tempIdentityMap, %edi
-	sub $BASE_DIFF, %edi
-
-	# Save the PTE into an entry in the identity map
-	mov %eax, (%edi, %ecx, 4)
-
-	# Increment count and loop
-	inc %ecx
-	mov $IMAGE_SIZE, %edx
-	add $256, %edx
-	cmp %edx, %ecx
-	jne 1b
-
-	# Load the physical address of the identity map, and generate a PDE
+	# Push physical address of identity map
 	mov $_tempIdentityMap, %eax
 	sub $BASE_DIFF, %eax
-	or $3, %eax
+	push %eax
 
-	# Load the physical address of the page directory
-	mov $_tempPgDir, %edi
-	sub $BASE_DIFF, %edi
-	
-	# Save the PDE to the first element in the page directory
-	mov %eax, (%edi)
-
-	# Load the physical address of the temporary page table, and generate a PDE
+	# Push physical address of page table
 	mov $_tempPgTable, %eax
 	sub $BASE_DIFF, %eax
-	or $3, %eax
+	push %eax
 
-	# Save the PDE to the entry corresponding to 0xC0000000
-	mov %eax, 4088(%edi)
-	
-	# Set the last entry in the page directory to point to the page directory itself
-	mov %edi, %eax
-	or $3, %eax
-	mov %eax, 4092(%edi)
+	# Push physical address of page directory
+	mov $_tempPgDir, %eax
+	sub $BASE_DIFF, %eax
+	push %eax
 
-	# Load the physical address of the page directory into CR3
-	mov $_tempPgDir, %edi
-	sub $BASE_DIFF, %edi
-	mov %edi, %cr3
-	
-	# Enable paging
-	mov %cr0, %eax
-	or $0x80010000, %eax
-	mov %eax, %cr0
+	# Load physical address of startPaging()
+	mov $startPaging, %eax
+	sub $BASE_DIFF, %eax
+
+	# Initialize paging
+	call *%eax
 
 	# Jump into mapped kernel binary
-	lea 2f, %eax
+	lea 1f, %eax
 	jmp *%eax
-2:
+1:
 	# Delete PDE corresponding to identity map. We shouldn't need it anymore.
 	movl $0, (_tempIdentityMap)
 
-	# Reload page tables
+	# Flush TLB
 	mov %cr3, %eax
 	mov %eax, %cr3
 
-	# Initialize stack
+	# Initialize stack in virtual memory
 	mov $stackTop, %esp
+
+	# Load GPT
 	lgdt gdt_info
 
+	# Load segment registers
 	jmp $8, $.ldcs
 .ldcs:	
 	mov $16, %ax
@@ -327,15 +200,27 @@ s_end:
 	mov %ax, %fs
 	mov %ax, %ss
 
-	mov $_bootCmdLine, %eax
-	push %eax
+	# Change EBX to point to the virtual address of the multiboot info
+	# If the new pointer is out-of-bounds, error
+	add $0xFF800000, %ebx
+	cmp $0xFF800000, %ebx
+	jl .err
+	cmp $0xFFC00000, %ebx
+	jge .err
+
+	# Call initialize(void* multibootInfo)
+	push %ebx
+	call initialize
+
+	# mov $_bootCmdLine, %eax
+	# push %eax
 	
 	# Call main function
-	call main
+	# call main
 
-_err:
+.err:
 	cli
-3:	hlt
-	jmp 3b
+2:	hlt
+	jmp 2b
 
 .size _start, . - _start