1、mkimage工具的源码

(1)mkimage是uboot下面的一个工具，用来将zImage制作成uImage，制作内核启动镜像(给zImage镜像添加64字节的头信息成uImage)；
(2)mkimage的源码在"uboot/tool"目录下，在编译uboot时默认会编译出mkimage工具；

2、mkimage工具的使用方法

root@daizhixin-virtual-machine:# ./mkimage 
Usage: ./mkimage -l image
          -l ==> list image header information
       ./mkimage [-x] -A arch -O os -T type -C comp -a addr -e ep -n name -d data_file[:data_file...] image
          -A ==> set architecture to 'arch' 
          -O ==> set operating system to 'os'	
          -T ==> set image type to 'type'
          -C ==> set compression type 'comp'
          -a ==> set load address to 'addr' (hex)
          -e ==> set entry point to 'ep' (hex)
          -n ==> set image name to 'name'
          -d ==> use image data from 'datafile'
          -x ==> set XIP (execute in place)
       ./mkimage [-D dtc_options] -f fit-image.its fit-image

3、mkimage添加的64字节头解析

/*
 * Operating System Codes
 */
#define IH_OS_INVALID		0	/* Invalid OS	*/
#define IH_OS_OPENBSD		1	/* OpenBSD	*/
#define IH_OS_NETBSD		2	/* NetBSD	*/
#define IH_OS_FREEBSD		3	/* FreeBSD	*/
#define IH_OS_4_4BSD		4	/* 4.4BSD	*/
#define IH_OS_LINUX		5	/* Linux	*/
#define IH_OS_SVR4		6	/* SVR4		*/
#define IH_OS_ESIX		7	/* Esix		*/
#define IH_OS_SOLARIS		8	/* Solaris	*/
#define IH_OS_IRIX		9	/* Irix		*/
#define IH_OS_SCO		10	/* SCO		*/
#define IH_OS_DELL		11	/* Dell		*/
#define IH_OS_NCR		12	/* NCR		*/
#define IH_OS_LYNXOS		13	/* LynxOS	*/
#define IH_OS_VXWORKS		14	/* VxWorks	*/
#define IH_OS_PSOS		15	/* pSOS		*/
#define IH_OS_QNX		16	/* QNX		*/
#define IH_OS_U_BOOT		17	/* Firmware	*/
#define IH_OS_RTEMS		18	/* RTEMS	*/
#define IH_OS_ARTOS		19	/* ARTOS	*/
#define IH_OS_UNITY		20	/* Unity OS	*/

/*
 * CPU Architecture Codes (supported by Linux)
 */
#define IH_ARCH_INVALID		0	/* Invalid CPU	*/
#define IH_ARCH_ALPHA		1	/* Alpha	*/
#define IH_ARCH_ARM		2	/* ARM		*/
#define IH_ARCH_I386		3	/* Intel x86	*/
#define IH_ARCH_IA64		4	/* IA64		*/
#define IH_ARCH_MIPS		5	/* MIPS		*/
#define IH_ARCH_MIPS64		6	/* MIPS	 64 Bit */
#define IH_ARCH_PPC		7	/* PowerPC	*/
#define IH_ARCH_S390		8	/* IBM S390	*/
#define IH_ARCH_SH		9	/* SuperH	*/
#define IH_ARCH_SPARC		10	/* Sparc	*/
#define IH_ARCH_SPARC64		11	/* Sparc 64 Bit */
#define IH_ARCH_M68K		12	/* M68K		*/
#define IH_ARCH_NIOS		13	/* Nios-32	*/
#define IH_ARCH_MICROBLAZE	14	/* MicroBlaze   */
#define IH_ARCH_NIOS2		15	/* Nios-II	*/
#define IH_ARCH_BLACKFIN	16	/* Blackfin	*/
#define IH_ARCH_AVR32		17	/* AVR32	*/
#define IH_ARCH_ST200	        18	/* STMicroelectronics ST200  */

/*
 * Image Types
 * /
#define IH_TYPE_INVALID		0	/* Invalid Image		*/
#define IH_TYPE_STANDALONE	1	/* Standalone Program		*/
#define IH_TYPE_KERNEL		2	/* OS Kernel Image		*/
#define IH_TYPE_RAMDISK		3	/* RAMDisk Image		*/
#define IH_TYPE_MULTI		4	/* Multi-File Image		*/
#define IH_TYPE_FIRMWARE	5	/* Firmware Image		*/
#define IH_TYPE_SCRIPT		6	/* Script file			*/
#define IH_TYPE_FILESYSTEM	7	/* Filesystem Image (any type)	*/
#define IH_TYPE_FLATDT		8	/* Binary Flat Device Tree Blob	*/

/*
 * Compression Types
 */
#define IH_COMP_NONE		0	/*  No	 Compression Used	*/
#define IH_COMP_GZIP		1	/* gzip	 Compression Used	*/
#define IH_COMP_BZIP2		2	/* bzip2 Compression Used	*/

#define IH_MAGIC	0x27051956	/* mkimage制作镜像的魔数Image Magic Number	*/
#define IH_NMLEN		32	/* Image Name Length	
/*
 * Legacy format image header,
 * all data in network byte order (aka natural aka bigendian).
 */
typedef struct image_header {
	uint32_t	ih_magic;	/* Image Header Magic Number	*/
	uint32_t	ih_hcrc;	/* Image Header CRC Checksum	*/
	uint32_t	ih_time;	/* Image Creation Timestamp	*/
	uint32_t	ih_size;	/* Image Data Size		*/
	uint32_t	ih_load;	/* Data	 Load  Address		*/
	uint32_t	ih_ep;		/* Entry Point Address		*/
	uint32_t	ih_dcrc;	/* Image Data CRC Checksum	*/
	uint8_t		ih_os;		/* Operating System		*/
	uint8_t		ih_arch;	/* CPU architecture		*/
	uint8_t		ih_type;	/* Image Type			*/
	uint8_t		ih_comp;	/* Compression Type		*/
	uint8_t		ih_name[IH_NMLEN];	/* Image Name		*/
} image_header_t;

image_header_t结构体定义在uboot源码的image.h中，和mkimage工具的使用参数是对应关系，mkimage工具就是构建image_header_t这样一个64字节头；

4、uImage和zIMage的比较

参考博客：《uImage的制作过程详解》；

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