嵌入式Linux--U-Boot（二）基本命令使用

落日映苍穹つ 2022-12-27 15:27 491阅读 0赞

### 目录 ###

*  一、进入UBoot命令行模式
 *  二、命令
 *   *  help命令
     *  信息查询命令
     *   *  1、bdinfo命令
         *  2、printenv命令
         *  3、version命令
     *  环境变量操作命令
     *   *  1、修改环境变量
         *   *  使用格式
         *  2、新建环境变量
         *  3、删除环境变量
     *  内存操作命令

# 一、进入UBoot命令行模式 #

上电以后，出现 `Hit any key to stop autoboot: 0`就按下任意键，出现`=>`符号就进入命令行模式了，如下：

U-Boot 2016.03 (Dec 12 2020 - 13:19:46 +0800)
    
    CPU:   Freescale i.MX6ULL rev1.1 69 MHz (running at 396 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 48C
    Reset cause: POR
    Board: MX6ULL 14x14 EVK
    I2C:   ready
    DRAM:  512 MiB
    MMC:   FSL_SDHC: 0, FSL_SDHC: 1
    *** Warning - bad CRC, using default environment
    
    Display: ATK-LCD-4.3-800x480 (800x480)
    Video: 800x480x24
    In:    serial
    Out:   serial
    Err:   serial
    switch to partitions #0, OK
    mmc1(part 0) is current device
    Net:   FEC1
    Error: FEC1 address not set.
    
    Normal Boot
    Hit any key to stop autoboot:  0

# 二、命令 #

## help命令 ##

=> help
    ?       - alias for 'help'
    base    - print or set address offset
    bdinfo  - print Board Info structure
    bmode   - sd1|sd2|qspi1|normal|usb|sata|ecspi1:0|ecspi1:1|ecspi1:2|ecspi1:3|esdhc1|esdhc2|esdhc3|esdhc4 [noreset]
    bmp     - manipulate BMP image data
    boot    - boot default, i.e., run 'bootcmd'
    bootd   - boot default, i.e., run 'bootcmd'
    bootelf - Boot from an ELF image in memory
    bootm   - boot application image from memory
    bootp   - boot image via network using BOOTP/TFTP protocol
    bootvx  - Boot vxWorks from an ELF image
    bootz   - boot Linux zImage image from memory
    clocks  - display clocks
    cmp     - memory compare
    coninfo - print console devices and information
    cp      - memory copy
    crc32   - checksum calculation
    dcache  - enable or disable data cache
    dhcp    - boot image via network using DHCP/TFTP protocol
    dm      - Driver model low level access
    echo    - echo args to console
    editenv - edit environment variable
    env     - environment handling commands
    erase   - erase FLASH memory
    exit    - exit script
    ext2load- load binary file from a Ext2 filesystem
    ext2ls  - list files in a directory (default /)
    ext4load- load binary file from a Ext4 filesystem
    ext4ls  - list files in a directory (default /)
    ext4size- determine a file's size ext4write- create a file in the root directory false - do nothing, unsuccessfully fatinfo - print information about filesystem fatload - load binary file from a dos filesystem fatls - list files in a directory (default /) fatsize - determine a file's size
    fatwrite- write file into a dos filesystem
    fdt     - flattened device tree utility commands
    flinfo  - print FLASH memory information
    fstype  - Look up a filesystem type
    fuse    - Fuse sub-system
    go      - start application at address 'addr'
    gpio    - query and control gpio pins
    help    - print command description/usage
    i2c     - I2C sub-system
    icache  - enable or disable instruction cache
    iminfo  - print header information for application image
    imxtract- extract a part of a multi-image
    itest   - return true/false on integer compare
    load    - load binary file from a filesystem
    loadb   - load binary file over serial line (kermit mode)
    loads   - load S-Record file over serial line
    loadx   - load binary file over serial line (xmodem mode)
    loady   - load binary file over serial line (ymodem mode)
    loop    - infinite loop on address range
    ls      - list files in a directory (default /)
    md      - memory display
    mdio    - MDIO utility commands
    mii     - MII utility commands
    mm      - memory modify (auto-incrementing address)
    mmc     - MMC sub system
    mmcinfo - display MMC info
    mtest   - simple RAM read/write test
    mw      - memory write (fill)
    nfs     - boot image via network using NFS protocol
    nm      - memory modify (constant address)
    ping    - send ICMP ECHO_REQUEST to network host
    pmic    - PMIC
    printenv- print environment variables
    protect - enable or disable FLASH write protection
    reset   - Perform RESET of the CPU
    run     - run commands in an environment variable
    save    - save file to a filesystem
    saveenv - save environment variables to persistent storage
    setenv  - set environment variables
    setexpr - set environment variable as the result of eval expression
    sf      - SPI flash sub-system
    showvar - print local hushshell variables
    size    - determine a file's size
    sleep   - delay execution for some time
    source  - run script from memory
    test    - minimal test like /bin/sh
    tftpboot- boot image via network using TFTP protocol
    true    - do nothing, successfully
    usb     - USB sub-system
    usbboot - boot from USB device
    version - print monitor, compiler and linker version
    =>

上面的那些命令并不是 uboot 所支持的所有命令，前面说过 uboot 是可配置的，需要什么命令就使能什么命令。所以上面的命令是正点原子提供的 uboot 中使能的命令，uboot 支持的命令还有很多，而且也可以在 uboot 中自定义命令。、

这些命令后面都跟有命令说明，用于描述此命令的作用，但是命令具体怎么用呢？

我们输入“help(或?) 命令名”既可以查看命令的详细用法，以“bootz”这个命令为例，我们输入如下命令即可查看“bootz”这个命令的用法：

=> ? bootz
    bootz - boot Linux zImage image from memory
    
    Usage:
    bootz [addr [initrd[:size]] [fdt]]
        - boot Linux zImage stored in memory
            The argument 'initrd' is optional and specifies the address
            of the initrd in memory. The optional argument ':size' allows
            specifying the size of RAW initrd.
            When booting a Linux kernel which requires a flat device-tree
            a third argument is required which is the address of the
            device-tree blob. To boot that kernel without an initrd image,
            use a '-' for the second argument. If you do not pass a third
            a bd_info struct will be passed instead

## 信息查询命令 ##

常用的和信息查询有关的命令有 3 个：

*  bdinfo
 *  printenv
 *  version

### 1、bdinfo命令 ###

先来看一下 bdinfo 命令，此命令用于查看板子信息，直接输入“bdinfo”即可，结果如下：

=> bdinfo
    arch_number = 0x00000000
    boot_params = 0x80000100
    DRAM bank   = 0x00000000
    -> start    = 0x80000000
    -> size     = 0x20000000
    eth0name    = FEC1
    ethaddr     = (not set)
    current eth = FEC1
    ip_addr     = <NULL>
    baudrate    = 115200 bps
    TLB addr    = 0x9FFF0000
    relocaddr   = 0x9FF51000
    reloc off   = 0x18751000
    irq_sp      = 0x9EF4EEA0
    sp start    = 0x9EF4EE90
    FB base     = 0x00000000

从上面中可以得出 DRAM 的起始地址和大小、启动参数保存起始地址、波特率、sp(堆栈指针)起始地址等信息。

### 2、printenv命令 ###

命令“printenv”用于输出环境变量信息，uboot 也支持 TAB 键自动补全功能，输入“print”然后按下 TAB 键就会自动补全命令，直接输入“print”也可以。输入“print”，然后按下回车键，环境变量如下面所示：

=> printenv
    baudrate=115200
    board_name=EVK
    board_rev=14X14
    boot_fdt=try
    bootcmd=run findfdt;mmc dev ${mmcdev};mmc dev ${mmcdev}; if mmc rescan; then if run loadbootscript; then run bootscript; else if run loadimage; then run mmcboot; else run netboot; fi; fi; else run netboot; fi
    bootcmd_mfg=run mfgtool_args;bootz ${loadaddr} ${initrd_addr} ${fdt_addr};
    bootdelay=1
    bootscript=echo Running bootscript from mmc ...; source
    console=ttymxc0
    ethact=FEC1
    ethprime=FEC
    fdt_addr=0x83000000
    fdt_file=imx6ull-14x14-emmc-4.3-800x480-c.dtb
    fdt_high=0xffffffff
    findfdt=if test $fdt_file = undefined; then if test $board_name = EVK && test $board_rev = 9X9; then setenv fdt_file imx6ull-9x9-evk.dtb; fi; if test $board_name = EVK && test $board_rev = 14X14; then setenv fdt_file imx6ull-14x14-evk.dtb; fi; if test $fdt_file = undefined; then echo WARNING: Could not determine dtb to use; fi; fi;
    image=zImage
    initrd_addr=0x83800000
    initrd_high=0xffffffff
    ip_dyn=yes
    loadaddr=0x80800000
    loadbootscript=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${script};
    loadfdt=fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}
    loadimage=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${image}
    logo_file=alientek.bmp
    mfgtool_args=setenv bootargs console=${console},${baudrate} rdinit=/linuxrc g_mass_storage.stall=0 g_mass_storage.removable=1 g_mass_storage.file=/fat g_mass_storage.ro=1 g_mass_storage.idVendor=0x066F g_mass_storage.idProduct=0x37FF g_mass_storage.iSerialNumber="" clk_ignore_unused
    mmcargs=setenv bootargs console=${console},${baudrate} root=${mmcroot}
    mmcautodetect=yes
    mmcboot=echo Booting from mmc ...; run mmcargs; if test ${boot_fdt} = yes || test ${boot_fdt} = try; then if run loadfdt; then bootz ${loadaddr} - ${fdt_addr}; else if test ${boot_fdt} = try; then bootz; else echo WARN: Cannot load the DT; fi; fi; else bootz; fi;
    mmcdev=1
    mmcpart=1
    mmcroot=/dev/mmcblk1p2 rootwait rw
    netargs=setenv bootargs console=${console},${baudrate} root=/dev/nfs ip=dhcp nfsroot=${serverip}:${nfsroot},v3,tcp
    netboot=echo Booting from net ...; run netargs; if test ${ip_dyn} = yes; then setenv get_cmd dhcp; else setenv get_cmd tftp; fi; ${get_cmd} ${image}; if test ${boot_fdt} = yes || test ${boot_fdt} = try; then if ${get_cmd} ${fdt_addr} ${fdt_file}; then bootz ${loadaddr} - ${fdt_addr}; else if test ${boot_fdt} = try; then bootz; else echo WARN: Cannot load the DT; fi; fi; else bootz; fi;
    panel=ATK-LCD-4.3-800x480
    script=boot.scr
    splashimage=0x88000000
    splashpos=m,m
    
    Environment size: 2536/8188 bytes

有很多的环境变量，比如 baudrate、board\_name、board\_rec、boot\_fdt、bootcmd等等。uboot 中的环境变量都是字符串，既然叫做环境变量，那么它的作用就和“变量”一样。

比如 **bootdelay** 这个环境变量就表示 uboot 启动延时时间，默认bootdelay=3，也就默认延时 3秒。前面说的 3 秒倒计时就是由 bootdelay 定义的，如果将 bootdelay 改为 5 的话就会倒计时 5s了。uboot 中的环境变量是可以修改的，有专门的命令来修改环境变量的值。

### 3、version命令 ###

命令 version 用于查看 uboot 的版本号，输入“version”，uboot 版本号如下所示：

=> version
    
    U-Boot 2016.03 (Dec 12 2020 - 13:19:46 +0800)
    arm-linux-gnueabihf-gcc (Linaro GCC 4.9-2017.01) 4.9.4
    GNU ld (Linaro_Binutils-2017.01) 2.24.0.20141017 Linaro 2014_11-3-git

## 环境变量操作命令 ##

### 1、修改环境变量 ###

环境变量的操作涉及到两个命令：

*  setenv ：用于设置或者修改环境变量的值
 *  saveenv：用于保存修改后的环境变量，一般环境变量是存放在外部 flash 中的，uboot 启动的时候会将环境变量从 flash 读取到 DRAM 中。**所以使用命令 setenv 修改的是 DRAM中的环境变量值，修改以后要使用 saveenv 命令将修改后的环境变量保存到 flash 中**，否则的话uboot 下一次重启会继续使用以前的环境变量值。

#### 使用格式 ####

比如我们要将环境变量 bootdelay 改为 5，就可以使用如下所示命令：

setenv bootdelay 5
    saveenv

如下：

=> setenv bootdelay 5
    => saveenv
    Saving Environment to MMC...
    Writing to MMC(1)... done

当我们使用命令 saveenv 保存修改后的环境变量的话会有保存过程提示信息，根据提示可以看出环境变量保存到了 MMC(1)中，也就是 EMMC 中。因为我用的 EMMC版本的核心板，所以会保存到MMC(1)中，如果是NAND版本核心板的话就会提示保存到NAND中。

修改 bootdelay 以后，重启开发板，uboot 就是变为 5 秒倒计时:

=> setenv bootdelay 5
    => saveenv
    Saving Environment to MMC...
    Writing to MMC(1)... done
    => reset
    resetting ...
    
    
    U-Boot 2016.03 (Dec 12 2020 - 13:19:46 +0800)
    
    CPU:   Freescale i.MX6ULL rev1.1 69 MHz (running at 396 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 57C
    Reset cause: WDOG
    Board: MX6ULL 14x14 EVK
    I2C:   ready
    DRAM:  512 MiB
    MMC:   FSL_SDHC: 0, FSL_SDHC: 1
    Display: ATK-LCD-4.3-800x480 (800x480)
    Video: 800x480x24
    In:    serial
    Out:   serial
    Err:   serial
    switch to partitions #0, OK
    mmc1(part 0) is current device
    Net:   FEC1
    Error: FEC1 address not set.
    
    Normal Boot
    Hit any key to stop autoboot:  5

有时候我们修改的环境变量值可能会有空格，比如 bootcmd、bootargs 等，这个时候环境变量值就得用单引号括起来，比如下面修改环境变量 bootargs 的值：

setenv bootargs 'console=ttymxc0,115200 root=/dev/mmcblk1p2 rootwait rw'
    saveenv

上面命令设置 bootargs 的值为“console=ttymxc0,115200 root=/dev/mmcblk1p2 rootwait rw”，其中“console=ttymxc0,115200”、“root=/dev/mmcblk1p2”、“rootwait”和“rw”相当于四组“值”，这四组“值”之间用空格隔开，所以需要使用单引号‘’将其括起来，表示这四组“值”都属于环境变量 bootargs。

### 2、新建环境变量 ###

命令 setenv 也可以用于新建命令，用法就是修改环境变量一样，比如我们新建一个环境变量 author，author 的值为我的名字音：liefyuan，那么就可以使用如下命令：

setenv author liefyuan
    saveenv

author 完成以后重启 uboot，然后使用命令 printenv 查看当前环境变量：

=> setenv author liefyuan
    => saveenv
    Saving Environment to MMC...
    Writing to MMC(1)... done
    => reset
    resetting ...
    
    
    U-Boot 2016.03 (Dec 12 2020 - 13:19:46 +0800)
    
    CPU:   Freescale i.MX6ULL rev1.1 69 MHz (running at 396 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 57C
    Reset cause: WDOG
    Board: MX6ULL 14x14 EVK
    I2C:   ready
    DRAM:  512 MiB
    MMC:   FSL_SDHC: 0, FSL_SDHC: 1
    Display: ATK-LCD-4.3-800x480 (800x480)
    Video: 800x480x24
    In:    serial
    Out:   serial
    Err:   serial
    switch to partitions #0, OK
    mmc1(part 0) is current device
    Net:   FEC1
    Error: FEC1 address not set.
    
    Normal Boot
    Hit any key to stop autoboot:  0
    => print
    author=liefyuan
    baudrate=115200
    board_name=EVK
    board_rev=14X14
    ...

### 3、删除环境变量 ###

既然可以新建环境变量，那么就可以删除环境变量，删除环境变量也是使用命令 setenv，要删除一个环境变量只要给这个环境变量赋空值即可，比如我们删除掉上面新建的 author 这个环境变量，命令如下：

setenv author
    saveenv

上面命令中通过 setenv 给 author 赋空值，也就是什么都不写来删除环境变量 author。重启uboot 就会发现环境变量 author 没有了:

=> setenv author
    => saveenv
    Saving Environment to MMC...
    Writing to MMC(1)... done
    => reset
    resetting ...
    
    
    U-Boot 2016.03 (Dec 12 2020 - 13:19:46 +0800)
    
    CPU:   Freescale i.MX6ULL rev1.1 69 MHz (running at 396 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 57C
    Reset cause: WDOG
    Board: MX6ULL 14x14 EVK
    I2C:   ready
    DRAM:  512 MiB
    MMC:   FSL_SDHC: 0, FSL_SDHC: 1
    Display: ATK-LCD-4.3-800x480 (800x480)
    Video: 800x480x24
    In:    serial
    Out:   serial
    Err:   serial
    switch to partitions #0, OK
    mmc1(part 0) is current device
    Net:   FEC1
    Error: FEC1 address not set.
    
    Normal Boot
    Hit any key to stop autoboot:  0
    => print
    baudrate=115200
    board_name=EVK
    board_rev=14X14

## 内存操作命令 ##