在uboot中加入cmd_run命令，运行环境变量

在学习uboot的过程中会经常烧录程序，每次都要敲一些下载指令。这样是不是很麻烦，有什么办法能快速的烧写呢。很简单，将需要敲击的指令编译到uboot中，以环境变量的形式存在。但是环境变量很好加，如何运行环境变量呢。这就需要自己加入run指令了。本文旨在简化uboot、linux内核及文件系统的烧录过程。

本文基于海思的Hi3531的uboot修改，首先在uboot目录下的include/configs/godnet.h中修改加入如下代码，增加烧写的环境变量。

#define CONFIG_BOOTDELAY    1
#define CONFIG_BOOTARGS "mem=64M console=ttyAMA0,115200 root=/dev/mtdblock2 rootfstype=jffs2 mtdparts=hi_sfc:1M(boot),4M(kernel),11M(rootfs)"
#define CONFIG_NETMASK  255.255.255.0       /* talk on MY local net */
#define CONFIG_IPADDR   192.168.0.251        /* static IP I currently own */
#define CONFIG_SERVERIP 192.168.0.27     /* current IP of tftp server ip */
#define CONFIG_ETHADDR  00:00:23:34:45:66
#define CONFIG_BOOTFILE "uImage"        /* file to load */
#define CONFIG_BAUDRATE         115200
#define CONFIG_UBOOT_BURN "mw.b 82000000 ff 100000;tftp 0x82000000 u-boot-ok.bin;sf probe 0;sf erase 0 100000;sf write 82000000 0 100000"
#define CONFIG_KERNEL_BURN "mw.b 82000000 ff 400000;tftp 82000000 uImage;sf probe 0;sf erase 100000 400000;sf write 82000000 100000 400000"
#define CONFIG_ROOT_BURN "mw.b 82000000 ff b00000; tftp 0x82000000 rootfs.jffs2;sf probe 0;sf erase 500000 b00000;sf write 82000000 500000 b00000"

其中，红色部分为加入的指令

CONFIG_UBOOT_BURN为烧写uboot的指令，CONFIG_KERNEL_BURN为烧写内核的指令，CONFIG_ROOT_BURN为烧写根文件系统的指令，具体指令内容不在详述；

还需要在环境变量的文件/common/env_common.c的default_environment数组中加入环境变量的值。具体代码如下：

uchar default_environment[] = {
#ifdef	CONFIG_BOOTARGS
"bootargs="	CONFIG_BOOTARGS			"\0"
#endif
#ifdef	CONFIG_BOOTCOMMAND
"bootcmd="	CONFIG_BOOTCOMMAND		"\0"
#endif
#ifdef	CONFIG_RAMBOOTCOMMAND
"ramboot="	CONFIG_RAMBOOTCOMMAND		"\0"
#endif
#ifdef	CONFIG_NFSBOOTCOMMAND
"nfsboot="	CONFIG_NFSBOOTCOMMAND		"\0"
#endif
#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0)
"bootdelay="	MK_STR(CONFIG_BOOTDELAY)	"\0"
#endif
#if defined(CONFIG_BAUDRATE) && (CONFIG_BAUDRATE >= 0)
"baudrate="	MK_STR(CONFIG_BAUDRATE)		"\0"
#endif
#ifdef	CONFIG_LOADS_ECHO
"loads_echo="	MK_STR(CONFIG_LOADS_ECHO)	"\0"
#endif
#ifdef	CONFIG_MDIO_INTF
"mdio_intf="	CONFIG_MDIO_INTF	        "\0"
#endif
#ifdef	CONFIG_ETHADDR
"ethaddr="	MK_STR(CONFIG_ETHADDR)		"\0"
#endif
#ifdef	CONFIG_ETH1ADDR
"eth1addr="	MK_STR(CONFIG_ETH1ADDR)		"\0"
#endif
#ifdef	CONFIG_ETH2ADDR
"eth2addr="	MK_STR(CONFIG_ETH2ADDR)		"\0"
#endif
#ifdef	CONFIG_ETH3ADDR
"eth3addr="	MK_STR(CONFIG_ETH3ADDR)		"\0"
#endif
#ifdef	CONFIG_ETH4ADDR
"eth4addr="	MK_STR(CONFIG_ETH4ADDR)		"\0"
#endif
#ifdef	CONFIG_ETH5ADDR
"eth5addr="	MK_STR(CONFIG_ETH5ADDR)		"\0"
#endif
#ifdef	CONFIG_IPADDR
"ipaddr="	MK_STR(CONFIG_IPADDR)		"\0"
#endif
#ifdef	CONFIG_SERVERIP
"serverip="	MK_STR(CONFIG_SERVERIP)		"\0"
#endif
#ifdef	CONFIG_SYS_AUTOLOAD
"autoload="	CONFIG_SYS_AUTOLOAD			"\0"
#endif
#ifdef	CONFIG_PREBOOT
"preboot="	CONFIG_PREBOOT			"\0"
#endif
#ifdef	CONFIG_ROOTPATH
"rootpath="	MK_STR(CONFIG_ROOTPATH)		"\0"
#endif
#ifdef	CONFIG_GATEWAYIP
"gatewayip="	MK_STR(CONFIG_GATEWAYIP)	"\0"
#endif
#ifdef	CONFIG_NETMASK
"netmask="	MK_STR(CONFIG_NETMASK)		"\0"
#endif
#ifdef	CONFIG_HOSTNAME
"hostname="	MK_STR(CONFIG_HOSTNAME)		"\0"
#endif
#ifdef	CONFIG_BOOTFILE
"bootfile="	MK_STR(CONFIG_BOOTFILE)		"\0"
#endif
#ifdef	CONFIG_LOADADDR
"loadaddr="	MK_STR(CONFIG_LOADADDR)		"\0"
#endif
#ifdef  CONFIG_CLOCKS_IN_MHZ
"clocks_in_mhz=1\0"
#endif
#if defined(CONFIG_PCI_BOOTDELAY) && (CONFIG_PCI_BOOTDELAY > 0)
"pcidelay="	MK_STR(CONFIG_PCI_BOOTDELAY)	"\0"
#endif
#ifdef CONFIG_UBOOT_BURN
"uboot_burn="	CONFIG_UBOOT_BURN			"\0"
#endif
#ifdef CONFIG_KERNEL_BURN
"kernel_burn="	CONFIG_KERNEL_BURN			"\0"
#endif
#ifdef CONFIG_ROOT_BURN
"root_burn="	CONFIG_ROOT_BURN			"\0"
#endif
#ifdef  CONFIG_EXTRA_ENV_SETTINGS
CONFIG_EXTRA_ENV_SETTINGS
#endif
"\0"
};

上述红色部分为加入的环境变量，其中uboot_burn，kernel_burn，root_burn为环境变量的名称。此后在uboot指令输入界面输入printenv可以看到变量值。

至此，环境变量修改完毕。下面如何在uboot中运行环境变量呢，其实只要能让uboot_burn变量中的内容执行即可。因此需要有一条指令可以运行这个环境变量。此时就需要cmd_run.c参与了。

在学习uboot时，我们知道在/common路径下面有很多以cmd_开头的文件，这些文件即使在uboot中可以运行的指令。但是，需要在配置文件和Makefile中添加支持。

首先我们把cmd_run.c文件创建了，代码如下：

/*
* (C) Copyright 2000-2003
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/

#include <common.h>
#include <command.h>

int do_run (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
{
int i;

if (argc < 2) {
cmd_usage(cmdtp);
return 1;
}

for (i=1; i<argc; ++i) {
char *arg;

if ((arg = getenv (argv[i])) == NULL) {
printf ("## Error: \"%s\" not defined\n", argv[i]);
return 1;
}
#ifndef CONFIG_SYS_HUSH_PARSER
if (run_command (arg, flag) == -1)
return 1;
#else
if (parse_string_outer(arg,
FLAG_PARSE_SEMICOLON | FLAG_EXIT_FROM_LOOP) != 0)
return 1;
#endif
}
return 0;
}

U_BOOT_CMD(
run,	CONFIG_SYS_MAXARGS,	1,	do_run,
"run commands in an environment variable",
"var [...]\n"
"    - run the commands in the environment variable(s) 'var'"
);

该C文件创建完，放入到common路径下，下面需要修改common路径下的Makefile，在文件中加入COBJS-y += cmd_run.o即可。这是将cmd_run.c加入编译选项中。在如下位置添加红色部分。

COBJS-$(CONFIG_CMD_I2C) += cmd_i2c.o
COBJS-$(CONFIG_CMD_IDE) += cmd_ide.o
COBJS-$(CONFIG_CMD_IMMAP) += cmd_immap.o
COBJS-$(CONFIG_CMD_IRQ) += cmd_irq.o
COBJS-$(CONFIG_CMD_ITEST) += cmd_itest.o
COBJS-$(CONFIG_CMD_JFFS2) += cmd_jffs2.o
COBJS-$(CONFIG_CMD_CRAMFS) += cmd_cramfs.o
COBJS-$(CONFIG_CMD_LICENSE) += cmd_license.o
COBJS-y += cmd_load.o

COBJS-y += cmd_run.o

至此run运行环境变量的方法已经添加完毕，按照正常的流程编译uboot，然后按照正常流程烧写。烧录成功后，在uboot运行指令界面输入run会出现如下界面

U-Boot 2010.06 (Oct 26 2015 - 10:15:14)

DRAM:  256 MiB
NAND:  Special Nand id table Version 1.35
Nand ID: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
No NAND device found!!!
0 MiB
Check spi flash
92f4
controller v300. found
Spi(cs1) ID: 0xEF 0x40 0x18 0x00 0x00 0x00
Spi(cs1): Block:64KB Chip:16MB Name:"W25Q128BV"
In:    serial
Out:   serial
Err:   serial
judge ddr init
user init finish.
Hit any key to stop autoboot:  0
hisilicon # run
run - run commands in an environment variable

hisilicon #

现在可以去运行刚刚添加的环境变量了，输入：“run uboot_burn”试试吧