| /* |
| * linux/arch/arm/boot/bootp/init.S |
| * |
| * Copyright (C) 2000-2003 Russell King. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * "Header" file for splitting kernel + initrd. Note that we pass |
| * r0 through to r3 straight through. |
| * |
| * This demonstrates how to append code to the start of the kernel |
| * zImage, and boot the kernel without copying it around. This |
| * example would be simpler; if we didn't have an object of unknown |
| * size immediately following the kernel, we could build this into |
| * a binary blob, and concatenate the zImage using the cat command. |
| */ |
| .section .start,#alloc,#execinstr |
| .type _start, #function |
| .globl _start |
| |
| _start: add lr, pc, #-0x8 @ lr = current load addr |
| adr r13, data |
| ldmia r13!, {r4-r6} @ r5 = dest, r6 = length |
| add r4, r4, lr @ r4 = initrd_start + load addr |
| bl move @ move the initrd |
| |
| /* |
| * Setup the initrd parameters to pass to the kernel. This can only be |
| * passed in via the tagged list. |
| */ |
| ldmia r13, {r5-r9} @ get size and addr of initrd |
| @ r5 = ATAG_CORE |
| @ r6 = ATAG_INITRD2 |
| @ r7 = initrd start |
| @ r8 = initrd end |
| @ r9 = param_struct address |
| |
| ldr r10, [r9, #4] @ get first tag |
| teq r10, r5 @ is it ATAG_CORE? |
| /* |
| * If we didn't find a valid tag list, create a dummy ATAG_CORE entry. |
| */ |
| movne r10, #0 @ terminator |
| movne r4, #2 @ Size of this entry (2 words) |
| stmneia r9, {r4, r5, r10} @ Size, ATAG_CORE, terminator |
| |
| /* |
| * find the end of the tag list, and then add an INITRD tag on the end. |
| * If there is already an INITRD tag, then we ignore it; the last INITRD |
| * tag takes precedence. |
| */ |
| taglist: ldr r10, [r9, #0] @ tag length |
| teq r10, #0 @ last tag (zero length)? |
| addne r9, r9, r10, lsl #2 |
| bne taglist |
| |
| mov r5, #4 @ Size of initrd tag (4 words) |
| stmia r9, {r5, r6, r7, r8, r10} |
| b kernel_start @ call kernel |
| |
| /* |
| * Move the block of memory length r6 from address r4 to address r5 |
| */ |
| move: ldmia r4!, {r7 - r10} @ move 32-bytes at a time |
| stmia r5!, {r7 - r10} |
| ldmia r4!, {r7 - r10} |
| stmia r5!, {r7 - r10} |
| subs r6, r6, #8 * 4 |
| bcs move |
| mov pc, lr |
| |
| .size _start, . - _start |
| |
| .align |
| |
| .type data,#object |
| data: .word initrd_start @ source initrd address |
| .word initrd_phys @ destination initrd address |
| .word initrd_size @ initrd size |
| |
| .word 0x54410001 @ r5 = ATAG_CORE |
| .word 0x54420005 @ r6 = ATAG_INITRD2 |
| .word initrd_phys @ r7 |
| .word initrd_size @ r8 |
| .word params_phys @ r9 |
| .size data, . - data |