diff options
| author | Ralf Baechle <ralf@linux-mips.org> | 1997-01-07 02:33:00 +0000 |
|---|---|---|
| committer | <ralf@linux-mips.org> | 1997-01-07 02:33:00 +0000 |
| commit | beb116954b9b7f3bb56412b2494b562f02b864b1 (patch) | |
| tree | 120e997879884e1b9d93b265221b939d2ef1ade1 /arch/i386/kernel/trampoline.S | |
| parent | 908d4681a1dc3792ecafbe64265783a86c4cccb6 (diff) | |
Import of Linux/MIPS 2.1.14
Diffstat (limited to 'arch/i386/kernel/trampoline.S')
| -rw-r--r-- | arch/i386/kernel/trampoline.S | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/arch/i386/kernel/trampoline.S b/arch/i386/kernel/trampoline.S new file mode 100644 index 000000000..29bcc9040 --- /dev/null +++ b/arch/i386/kernel/trampoline.S @@ -0,0 +1,74 @@ +! +! Trampoline.S Derived from Setup.S by Linus Torvalds +! +! Entry: CS:IP point to the start of our code, we are +! in real mode with no stack, but the rest of the +! trampoline page to make our stack and everything else +! is a mystery. +! +! In fact we don't actually need a stack so we don't +! set one up. +! +! We jump into the boot/compressed/head.S code. So you'd +! better be running a compressed kernel image or you +! won't get very far. +! +#define __ASSEMBLY__ +#include <asm/segment.h> + +.text + extrn startup32 + +entry start +start: +! nop +! jmp start ! Test + mov ax,cs ! Code and data in the same place + mov ds,ax ! + mov cx,ax ! Pass stack info to the 32bit boot + add cx,cx + add cx,cx + add cx,cx + add cx,cx ! Segment -> Offset + add cx, #4096 ! End of page is wanted + mov bx,#1 ! Flag an SMP trampoline + cli ! We should be safe anyway + + lidt idt_48 ! load idt with 0,0 + lgdt gdt_48 ! load gdt with whatever is appropriate + + xor ax,ax + inc ax ! protected mode (PE) bit + lmsw ax ! Into protected mode + jmp flush_instr +flush_instr: + jmpi 8192+startup32,KERNEL_CS ! Jump to the 32bit trampoline code +! jmpi 0x100000,KERNEL_CS ! Jump into the 32bit startup +! .byte 0x66,0x67 ! 32bit +! .byte 0xea,0x00,0x00,0x10,0x00,0x10,0x00 !jmpi .0x100000,KERNEL_CS + +gdt: + .word 0,0,0,0 ! dummy + + .word 0,0,0,0 ! unused + + .word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb) + .word 0x0000 ! base address=0 + .word 0x9A00 ! code read/exec + .word 0x00C0 ! granularity=4096, 386 + + .word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb) + .word 0x0000 ! base address=0 + .word 0x9200 ! data read/write + .word 0x00C0 ! granularity=4096, 386 + +idt_48: + .word 0 ! idt limit=0 + .word 0,0 ! idt base=0L + +gdt_48: + .word 0x800 ! gdt limit=2048, 256 GDT entries + .word 8192+gdt,0x0 ! gdt base = 8192+gdt (first SMP CPU) + ! we load the others with the first table + ! saves rewriting gdt_48 for each + |