69 lines
1.4 KiB
ArmAsm
69 lines
1.4 KiB
ArmAsm
.set MBALIGN, 1<<0 # align loaded modules on page boundaries
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.set MEMINFO, 1<<1 # provide memory map
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.set FLAGS, MBALIGN | MEMINFO # this is the Multiboot 'flag' field
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.set MAGIC, 0x1BADB002 # 'magic number' lets bootloader find the header
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.set CHECKSUM, -(MAGIC + FLAGS) # checksum of above, to prove we are multiboot
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.section .multiboot
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.align 4
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.long MAGIC
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.long FLAGS
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.long CHECKSUM
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.section .bootstrap_stack, "aw", @nobits
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.align 16
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stack_bottom:
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.skip 16384 # 16 KiB
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stack_top:
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.section .bss, "aw", @nobits
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.align 4096
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boot_pagedir:
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.skip 4096
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boot_pagetab1:
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.skip 4096
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.section .text
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.global _start
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.type _start, @function
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_start:
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mov $(boot_pagetab1 - 0xC0000000), %edi
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mov $0, %esi
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mov $1023, %ecx
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1:
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cmp $(_kernel_start - 0xC0000000), %esi
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jl 2f
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# + 0x1000 for the GRUB memory map
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cmp $(_kernel_end - 0xC0000000 + 0x1000), %esi
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jge 3f
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mov %esi, %edx
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or $0x003, %edx
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mov %edx, (%edi)
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2:
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add $4096, %esi
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add $4, %edi
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loop 1b
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3:
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movl $(boot_pagetab1 - 0xC0000000 + 0x003), boot_pagedir - 0xC0000000 + 0
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movl $(boot_pagetab1 - 0xC0000000 + 0x003), boot_pagedir - 0xC0000000 + 768 * 4
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movl $(boot_pagedir - 0xC0000000), %ecx
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mov %ecx, %cr3
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mov %cr0, %ecx
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or $0x80010000, %ecx
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mov %ecx, %cr0
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lea 4f, %ecx
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jmp *%ecx
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4:
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movl $0, boot_pagedir + 0
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mov %cr3, %ecx
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mov %ecx, %cr3
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mov $stack_top, %esp
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call kernel_main
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cli
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.hang: hlt
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jmp .hang
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.end:
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.size _start, . - _start
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