diff options
author | Sebastian Schmelzer | 2010-10-25 16:53:54 +0200 |
---|---|---|
committer | Sebastian Schmelzer | 2010-10-25 16:53:54 +0200 |
commit | 3050a9253437f4a4b5ad4bf3b3efdc3c660a5137 (patch) | |
tree | 91ac22153e416aac7ca20916b314b5e2ffa871b1 /contrib/syslinux-4.02/memdisk/start32.S | |
download | preboot-master.tar.gz preboot-master.tar.xz preboot-master.zip |
Diffstat (limited to 'contrib/syslinux-4.02/memdisk/start32.S')
-rw-r--r-- | contrib/syslinux-4.02/memdisk/start32.S | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/memdisk/start32.S b/contrib/syslinux-4.02/memdisk/start32.S new file mode 100644 index 0000000..4fb0537 --- /dev/null +++ b/contrib/syslinux-4.02/memdisk/start32.S @@ -0,0 +1,101 @@ +/* ----------------------------------------------------------------------- + * + * Copyright 2003-2009 H. Peter Anvin - All Rights Reserved + * Copyright 2009 Intel Corporation; author: H. Peter Anvin + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, + * Boston MA 02110-1301, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/* + * Simple stub to get us to the right point in the 32-bit code; + * this module must be linked first + */ + + .section ".init", "ax" + .globl _start +_start: + /* Zero the bss */ + cld + movl $__bss_start, %edi + movl $__bss_end, %ecx + subl %edi, %ecx + xorl %eax, %eax + shrl $2, %ecx + rep ; stosl + + /* Set up the protected-mode IDT and the interrupt jump buffers */ + movl $idt, %edi + movl $ijb, %eax + movl $0xee000000, %ebx /* Interrupt gate */ + movw %cs, %bx /* Target segment */ + + /* Make the IDT */ + movl $256, %ecx +1: + stosl + stosl + movl %ebx, -6(%edi) + addl $8, %eax + loop 1b + + /* + * Each entry in the interrupt jump buffer contains the following + * instructions: + * + * 60 pushal + * b0xx movb $xx, %al # interrupt number + * e9xxxxxxxx jmp handle_interrupt + */ + movl $0xe900b060, %eax + movl $256, %ecx +1: + movl %eax, (%edi) + addl $(1 << 16), %eax + movl $handle_interrupt-8, %edx + subl %edi, %edx + movl %edx, 4(%edi) + addl $8, %edi + loop 1b + + lidtl idt_ptr + + /* Save arguments, switch stacks */ + movl %esp, %eax /* Pointer to arguments */ + movl $__stack_end, %esp + + call setup + jmp *(rm_args) /* First argument is return */ + + .section ".text","ax" + .globl intcall + .type intcall, @function +intcall: + jmp *(rm_args+1*4) /* Intcall is argument 1 */ + .size intcall, .-intcall + + .type handle_interrupt, @function +handle_interrupt: + jmp *(rm_args+4*4) /* Interrupt pointer is argument 4 */ + .size handle_interrupt, .-handle_interrupt + + .section ".rodata","a" +idt_ptr: + .word 8*256-1 + .long idt + .word 0 + + .section ".bss.large","aw" + .balign 2048 +idt: + .space 8*256 +ijb: + .space 8*256 + +__stack: + .space 65536 +__stack_end: |