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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/x86_64/kernel/trampoline.S
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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1/*
2 *
3 * Trampoline.S Derived from Setup.S by Linus Torvalds
4 *
5 * 4 Jan 1997 Michael Chastain: changed to gnu as.
6 *
7 * Entry: CS:IP point to the start of our code, we are
8 * in real mode with no stack, but the rest of the
9 * trampoline page to make our stack and everything else
10 * is a mystery.
11 *
12 * In fact we don't actually need a stack so we don't
13 * set one up.
14 *
15 * On entry to trampoline_data, the processor is in real mode
16 * with 16-bit addressing and 16-bit data. CS has some value
17 * and IP is zero. Thus, data addresses need to be absolute
18 * (no relocation) and are taken with regard to r_base.
19 *
20 * If you work on this file, check the object module with objdump
21 * --full-contents --reloc to make sure there are no relocation
22 * entries. For the GDT entry we do hand relocation in smpboot.c
23 * because of 64bit linker limitations.
24 */
25
26#include <linux/linkage.h>
27#include <asm/segment.h>
28#include <asm/page.h>
29
30.data
31
32.code16
33
34ENTRY(trampoline_data)
35r_base = .
36 wbinvd
37 mov %cs, %ax # Code and data in the same place
38 mov %ax, %ds
39
40 cli # We should be safe anyway
41
42 movl $0xA5A5A5A5, trampoline_data - r_base
43 # write marker for master knows we're running
44
45 lidt idt_48 - r_base # load idt with 0, 0
46 lgdt gdt_48 - r_base # load gdt with whatever is appropriate
47
48 xor %ax, %ax
49 inc %ax # protected mode (PE) bit
50 lmsw %ax # into protected mode
51 # flaush prefetch and jump to startup_32 in arch/x86_64/kernel/head.S
52 ljmpl $__KERNEL32_CS, $(startup_32-__START_KERNEL_map)
53
54 # Careful these need to be in the same 64K segment as the above;
55idt_48:
56 .word 0 # idt limit = 0
57 .word 0, 0 # idt base = 0L
58
59gdt_48:
60 .short __KERNEL32_CS + 7 # gdt limit
61 .long cpu_gdt_table-__START_KERNEL_map
62
63.globl trampoline_end
64trampoline_end: