U-Boot启动引导内核分析(三).doc

U-Boot启动引导内核分析(三) 2011-03-23 09:20:51| 分类： 默认分类 | 标签： |字号大中小 订阅do_bootm_linux()函数位于lib_arm/Bootm.c文件中，主要流程分析如下：void do_bootm_linux (cmd_tbl_t *cmdtp, int flag, int argc, char *argv, bootm_headers_t *images) ulong initrd_start, initrd_end; ulong ep = 0; bd_t *bd = gd-bd; char *s; int machid = bd-bi_arch_number; void (*theKernel)(int zero, int arch, uint params); int ret;#ifdef CONFIG_CMDLINE_TAG char *commandline = getenv (bootargs);#endif /* find kernel entry point */ if (images-legacy_hdr_valid) ep = image_get_ep (&images-legacy_hdr_os_copy);#if defined(CONFIG_FIT) else if (images-fit_uname_os) ret = fit_image_get_entry (images-fit_hdr_os, images-fit_noffset_os, &ep); if (ret) puts (Cant get entry point property!n); goto error; #endif else puts (Could not find kernel entry point!n); goto error; theKernel = (void (*)(int, int, uint)ep; s = getenv (machid); if (s) machid = simple_strtoul (s, NULL, 16); printf (Using machid 0x%x from environmentn, machid); ret = boot_get_ramdisk (argc, argv, images, IH_ARCH_ARM, &initrd_start, &initrd_end); if (ret) goto error; show_boot_progress (15); debug (# Transferring control to Linux (at address %08lx) .n, (ulong) theKernel);#if defined (CONFIG_SETUP_MEMORY_TAGS) | defined (CONFIG_CMDLINE_TAG) | defined (CONFIG_INITRD_TAG) | defined (CONFIG_SERIAL_TAG) | defined (CONFIG_REVISION_TAG) | defined (CONFIG_LCD) | defined (CONFIG_VFD) /* 初始化TAG结构体开始 */ setup_start_tag (bd);#ifdef CONFIG_SERIAL_TAG setup_serial_tag (¶ms);#endif#ifdef CONFIG_REVISION_TAG setup_revision_tag (¶ms);#endif#ifdef CONFIG_SETUP_MEMORY_TAGS /* 设置RAM参数 */ setup_memory_tags (bd);#endif#ifdef CONFIG_CMDLINE_TAG setup_commandline_tag (bd, commandline);#endif#ifdef CONFIG_INITRD_TAG if (initrd_start & initrd_end) setup_initrd_tag (bd, initrd_start, initrd_end);#endif#if defined (CONFIG_VFD) | defined (CONFIG_LCD) setup_videolfb_tag (gd_t *) gd);#endif /* 初始化TAG结构体结束 */ setup_end_tag (bd);#endif /* we assume that the kernel is in place */ printf (nStarting kernel .nn);#ifdef CONFIG_USB_DEVICE extern void udc_disconnect (void); udc_disconnect (); #endif cleanup_before_linux (); /* 将控制权交给内核，让内核自解压启动 */ /* 传给KERNEL的参数：（struct tag *）bd-bi_boot_params */ /* 在boardatmelat91sam9g20ekAt91sam9g20ek.c文件中有如下定义： gd-bd-bi_boot_params = PHYS_SDRAM + 0x100;(PHYS_SDRAM = 0x20000000) */