ARM Linux BOOTLOADER全程详解（5） memory, linux, 仿真器, Linux, FLASH

yuyang911220

//获得可用memory 信息,做成列表,后面会作为启动参数传给KERNEL
//所谓内存映射就是指在4GB 物理地址空间中有哪些地址范围被分配用来寻址系统的 RAM 单元。
Uart_SendString("/n/tMemory Map Successful!/n");
/*我用仿真器把KERNEL,RAMDISK直接放在SDRAM上,所以下面这段是不需要的,但是如果KERNEL,RAMDISK在FLASH里,那就需要. */
/*******************(copy linux KERNEL)*******************/
Uart_SendString("/tLoading KERNEL IMAGE from FLASH... /n ");
Uart_SendString("/tand copy KERNEL IMAGE to SDRAM at 0x31000000/n");
Uart_SendString("/t/tby LEIJUN DONG dongleijun4000@hotmail.com /n");
//3*1024*1024/32linux KERNEL des,src,length=3M
for(k = 0;k < 196608;k++,downPt += 1,fromPt += 1)
* (u32 *)downPt = * (u32 *)fromPt;
/*******************(load RAMDISK)*******************/
Uart_SendString("/t/tloading COMPRESSED RAMDISK.../n");
downPt=(RAM_COMPRESSED_RAMDISK_BASE);
fromPt=(FLASH_RAMDISK_BASE);
//3*1024*1024/32linux KERNEL des,src,length=3M
for(k = 0;k < 196608;k++,downPt += 1,fromPt += 1)
* (u32 *)downPt = * (u32 *)fromPt;
/******jffs2文件系统,在开发中如果用不到FLASH,这段也可以不要********/
Uart_SendString("/t/tloading jffs2.../n");
downPt=(RAM_JFFS2);
fromPt=(FLASH_JFFS2);
for(k = 0;k < (1024*1024/32);k++,downPt += 1,fromPt += 1)
* (u32 *)downPt = * (u32 *)fromPt;
Uart_SendString( "Load Success...Run.../n ");
/*******************(setup param)*******************/
setup_start_tag();//开始设置启动参数
setup_memory_tags();//内存印象
setup_commandline_tag("console=ttyS0,115200n8");//启动命令行
setup_initrd2_tag();//root device
setup_RAMDISK_tag();//ramdisk image
setup_end_tag();
/*关I-cache */
asm ("mrc p15, 0, %0, c1, c0, 0": "=r" (i));
i &= ~0x1000;
asm ("mcr p15, 0, %0, c1, c0, 0": : "r" (i));
/* flush I-cache */
asm ("mcr p15, 0, %0, c7, c5, 0": : "r" (i));
//下面这行就跳到了COMPRESSED KERNEL的首地址
theKERNEL(0, ARCH_NUMBER, (unsigned long *)(RAM_BOOT_PARAMS));
/*启动kernel时候,I-cache可以开也可以关,r0必须是0,r1必须是CPU型号
(可以从linux/arch/arm/tools/mach-types中找到),r2必须是参数的物理开始地址*/
/*******************END*******************/
error:
Uart_SendString("/n/nPanic SDRAM check error!/n");
return 0;
}
static void setup_start_tag(void)
{
params = (struct tag *)RAM_BOOT_PARAMS;//启动参数开始的地址
params->hdr.tag = ATAG_CORE;
params->hdr.size = tag_size(tag_core);
params->u.core.flags = 0;
params->u.core.pagesize = 0;
params->u.core.rootdev = 0;
params = tag_next(params);
}