diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/i386/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!
Diffstat (limited to 'arch/i386/kernel/trampoline.S')
-rw-r--r-- | arch/i386/kernel/trampoline.S | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/arch/i386/kernel/trampoline.S b/arch/i386/kernel/trampoline.S new file mode 100644 index 000000000000..fcce0e61b0e7 --- /dev/null +++ b/arch/i386/kernel/trampoline.S | |||
@@ -0,0 +1,80 @@ | |||
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 | * This is only used for booting secondary CPUs in SMP machine | ||
8 | * | ||
9 | * Entry: CS:IP point to the start of our code, we are | ||
10 | * in real mode with no stack, but the rest of the | ||
11 | * trampoline page to make our stack and everything else | ||
12 | * is a mystery. | ||
13 | * | ||
14 | * In fact we don't actually need a stack so we don't | ||
15 | * set one up. | ||
16 | * | ||
17 | * We jump into the boot/compressed/head.S code. So you'd | ||
18 | * better be running a compressed kernel image or you | ||
19 | * won't get very far. | ||
20 | * | ||
21 | * On entry to trampoline_data, the processor is in real mode | ||
22 | * with 16-bit addressing and 16-bit data. CS has some value | ||
23 | * and IP is zero. Thus, data addresses need to be absolute | ||
24 | * (no relocation) and are taken with regard to r_base. | ||
25 | * | ||
26 | * If you work on this file, check the object module with | ||
27 | * objdump --reloc to make sure there are no relocation | ||
28 | * entries except for: | ||
29 | * | ||
30 | * TYPE VALUE | ||
31 | * R_386_32 startup_32_smp | ||
32 | * R_386_32 boot_gdt_table | ||
33 | */ | ||
34 | |||
35 | #include <linux/linkage.h> | ||
36 | #include <asm/segment.h> | ||
37 | #include <asm/page.h> | ||
38 | |||
39 | .data | ||
40 | |||
41 | .code16 | ||
42 | |||
43 | ENTRY(trampoline_data) | ||
44 | r_base = . | ||
45 | wbinvd # Needed for NUMA-Q should be harmless for others | ||
46 | mov %cs, %ax # Code and data in the same place | ||
47 | mov %ax, %ds | ||
48 | |||
49 | cli # We should be safe anyway | ||
50 | |||
51 | movl $0xA5A5A5A5, trampoline_data - r_base | ||
52 | # write marker for master knows we're running | ||
53 | |||
54 | /* GDT tables in non default location kernel can be beyond 16MB and | ||
55 | * lgdt will not be able to load the address as in real mode default | ||
56 | * operand size is 16bit. Use lgdtl instead to force operand size | ||
57 | * to 32 bit. | ||
58 | */ | ||
59 | |||
60 | lidtl boot_idt - r_base # load idt with 0, 0 | ||
61 | lgdtl boot_gdt - r_base # load gdt with whatever is appropriate | ||
62 | |||
63 | xor %ax, %ax | ||
64 | inc %ax # protected mode (PE) bit | ||
65 | lmsw %ax # into protected mode | ||
66 | # flush prefetch and jump to startup_32_smp in arch/i386/kernel/head.S | ||
67 | ljmpl $__BOOT_CS, $(startup_32_smp-__PAGE_OFFSET) | ||
68 | |||
69 | # These need to be in the same 64K segment as the above; | ||
70 | # hence we don't use the boot_gdt_descr defined in head.S | ||
71 | boot_gdt: | ||
72 | .word __BOOT_DS + 7 # gdt limit | ||
73 | .long boot_gdt_table-__PAGE_OFFSET # gdt base | ||
74 | |||
75 | boot_idt: | ||
76 | .word 0 # idt limit = 0 | ||
77 | .long 0 # idt base = 0L | ||
78 | |||
79 | .globl trampoline_end | ||
80 | trampoline_end: | ||