!
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!
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! Trampoline.S Derived from Setup.S by Linus Torvalds
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! Trampoline.S Derived from Setup.S by Linus Torvalds
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!
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!
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! Entry: CS:IP point to the start of our code, we are
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! Entry: CS:IP point to the start of our code, we are
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! in real mode with no stack, but the rest of the
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! in real mode with no stack, but the rest of the
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! trampoline page to make our stack and everything else
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! trampoline page to make our stack and everything else
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! is a mystery.
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! is a mystery.
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!
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!
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! In fact we don't actually need a stack so we don't
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! In fact we don't actually need a stack so we don't
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! set one up.
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! set one up.
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!
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!
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! We jump into the boot/compressed/head.S code. So you'd
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! We jump into the boot/compressed/head.S code. So you'd
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! better be running a compressed kernel image or you
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! better be running a compressed kernel image or you
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! won't get very far.
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! won't get very far.
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!
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!
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#define __ASSEMBLY__
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#define __ASSEMBLY__
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#include
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#include
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.text
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.text
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extrn startup32
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extrn startup32
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entry start
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entry start
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start:
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start:
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! nop
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! nop
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! jmp start ! Test
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! jmp start ! Test
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mov ax,cs ! Code and data in the same place
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mov ax,cs ! Code and data in the same place
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mov ds,ax !
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mov ds,ax !
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mov cx,ax ! Pass stack info to the 32bit boot
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mov cx,ax ! Pass stack info to the 32bit boot
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add cx,cx
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add cx,cx
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add cx,cx
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add cx,cx
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add cx,cx
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add cx,cx
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add cx,cx ! Segment -> Offset
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add cx,cx ! Segment -> Offset
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add cx, #4096 ! End of page is wanted
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add cx, #4096 ! End of page is wanted
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mov bx,#1 ! Flag an SMP trampoline
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mov bx,#1 ! Flag an SMP trampoline
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cli ! We should be safe anyway
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cli ! We should be safe anyway
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lidt idt_48 ! load idt with 0,0
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lidt idt_48 ! load idt with 0,0
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lgdt gdt_48 ! load gdt with whatever is appropriate
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lgdt gdt_48 ! load gdt with whatever is appropriate
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xor ax,ax
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xor ax,ax
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inc ax ! protected mode (PE) bit
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inc ax ! protected mode (PE) bit
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lmsw ax ! Into protected mode
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lmsw ax ! Into protected mode
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jmp flush_instr
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jmp flush_instr
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flush_instr:
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flush_instr:
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jmpi 8192+startup32,KERNEL_CS ! Jump to the 32bit trampoline code
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jmpi 8192+startup32,KERNEL_CS ! Jump to the 32bit trampoline code
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! jmpi 0x100000,KERNEL_CS ! Jump into the 32bit startup
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! jmpi 0x100000,KERNEL_CS ! Jump into the 32bit startup
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! .byte 0x66,0x67 ! 32bit
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! .byte 0x66,0x67 ! 32bit
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! .byte 0xea,0x00,0x00,0x10,0x00,0x10,0x00 !jmpi .0x100000,KERNEL_CS
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! .byte 0xea,0x00,0x00,0x10,0x00,0x10,0x00 !jmpi .0x100000,KERNEL_CS
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gdt:
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gdt:
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.word 0,0,0,0 ! dummy
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.word 0,0,0,0 ! dummy
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|
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.word 0,0,0,0 ! unused
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.word 0,0,0,0 ! unused
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.word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb)
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.word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb)
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.word 0x0000 ! base address=0
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.word 0x0000 ! base address=0
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.word 0x9A00 ! code read/exec
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.word 0x9A00 ! code read/exec
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.word 0x00C0 ! granularity=4096, 386
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.word 0x00C0 ! granularity=4096, 386
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.word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb)
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.word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb)
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.word 0x0000 ! base address=0
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.word 0x0000 ! base address=0
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.word 0x9200 ! data read/write
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.word 0x9200 ! data read/write
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.word 0x00C0 ! granularity=4096, 386
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.word 0x00C0 ! granularity=4096, 386
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idt_48:
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idt_48:
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.word 0 ! idt limit=0
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.word 0 ! idt limit=0
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.word 0,0 ! idt base=0L
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.word 0,0 ! idt base=0L
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gdt_48:
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gdt_48:
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.word 0x800 ! gdt limit=2048, 256 GDT entries
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.word 0x800 ! gdt limit=2048, 256 GDT entries
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.word 8192+gdt,0x0 ! gdt base = 8192+gdt (first SMP CPU)
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.word 8192+gdt,0x0 ! gdt base = 8192+gdt (first SMP CPU)
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! we load the others with the first table
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! we load the others with the first table
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! saves rewriting gdt_48 for each
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! saves rewriting gdt_48 for each
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