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ee4d7c18c8
The old bootloader was hilariously complicated, requiring a floppy disk with the kernel on it, and a hard drive with the file system. This patch removes the floppy disk from the equation and replaces it with a multiboot header. This means the kernel can now be booted with qemu-system-i386 -kernel kernel
65 lines
1.2 KiB
ArmAsm
65 lines
1.2 KiB
ArmAsm
.set MULTIBOOT_MAGIC, 0x1badb002
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.set MULTIBOOT_PAGE_ALIGN, 0x1
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.set MULTIBOOT_MEMORY_INFO, 0x2
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.set MULTIBOOT_VIDEO_MODE, 0x4
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.set multiboot_flags, MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_VIDEO_MODE
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.set multiboot_checksum, -(MULTIBOOT_MAGIC + multiboot_flags)
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.section .multiboot
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.align 4
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.long MULTIBOOT_MAGIC
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.long multiboot_flags
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.long multiboot_checksum
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/* for MULTIBOOT_MEMORY_INFO */
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.long 0x00000000 /* header_addr */
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.long 0x00000000 /* load_addr */
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.long 0x00000000 /* load_end_addr */
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.long 0x00000000 /* bss_end_addr */
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.long 0x00000000 /* entry_addr */
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/* for MULTIBOOT_VIDEO_MODE */
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.long 0x00000000 /* mode_type */
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.long 0 /* width */
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.long 0 /* height */
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.long 32 /* depth */
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.section .stack, "aw", @nobits
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stack_bottom:
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.skip 32768
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stack_top:
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.section .text
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.global start
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.type start, @function
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.extern init
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.type init, @function
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start:
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mov $stack_top, %esp
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and $-16, %esp
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pushl %esp
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pushl %eax /* Multiboot header magic */
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pushl %ebx /* Multiboot header pointer */
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cli
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call init
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pushl $exit_message
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call kprintf
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cli
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loop:
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hlt
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jmp loop
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exit_message:
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.asciz "Kernel exited."
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