66ba8079c7
Allocate proper kernel page table immediately in main using boot allocator Remove pginit Simplify address space layout a tiny bit More to come (e.g., superpages to simplify static table)
76 lines
2 KiB
ArmAsm
76 lines
2 KiB
ArmAsm
# Multiboot header, for multiboot boot loaders like GNU Grub.
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# http://www.gnu.org/software/grub/manual/multiboot/multiboot.html
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#
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# Using GRUB 2, you can boot xv6 from a file stored in a
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# Linux file system by copying kernel or kernelmemfs to /boot
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# and then adding this menu entry:
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#
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# menuentry "xv6" {
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# insmod ext2
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# set root='(hd0,msdos1)'
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# set kernel='/boot/kernel'
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# echo "Loading ${kernel}..."
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# multiboot ${kernel} ${kernel}
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# boot
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# }
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#include "asm.h"
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#include "memlayout.h"
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#include "mmu.h"
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#define STACK 4096
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# Multiboot header. Data to direct multiboot loader.
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.p2align 2
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.text
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.globl multiboot_header
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multiboot_header:
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#define magic 0x1badb002
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#define flags (1<<16 | 1<<0)
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.long magic
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.long flags
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.long (-magic-flags)
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.long multiboot_header # beginning of image
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.long multiboot_header
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.long edata
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.long end
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.long multiboot_entry
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# Multiboot entry point. Machine is mostly set up.
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# Configure the GDT to match the environment that our usual
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# boot loader - bootasm.S - sets up.
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.globl multiboot_entry
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multiboot_entry:
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# lgdt V2P_WO(gdtdesc)
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# ljmp $(SEG_KCODE<<3), $mbstart32
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mbstart32:
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# Set up the protected-mode data segment registers
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movw $(SEG_KDATA<<3), %ax # Our data segment selector
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movw %ax, %ds # -> DS: Data Segment
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movw %ax, %es # -> ES: Extra Segment
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movw %ax, %ss # -> SS: Stack Segment
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movw $0, %ax # Zero segments not ready for use
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movw %ax, %fs # -> FS
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movw %ax, %gs # -> GS
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movl $(V2P_WO(bootpgdir)), %eax
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movl %eax, %cr3
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# Turn on paging.
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movl %cr0, %eax
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orl $(CR0_PE|CR0_PG|CR0_WP), %eax
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movl %eax, %cr0
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# now switch to using addresses above KERNBASE
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# call addresses are pc-relative so we jump though this hoop:
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mov $relocated, %eax
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jmp *%eax
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relocated:
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# Set up the stack pointer and call into C.
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movl $(stack + STACK), %esp
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call main
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spin:
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jmp spin
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.comm stack, STACK
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