Linux学习笔记（7）——u-boot常用指令
- 信息查询命令
1.1. bdinfo命令：命令用于查看板子信息
如正点原子linux alpha开发板信息
=> bdinfo
arch_number = 0x00000000
boot_params = 0x80000100
DRAM bank = 0x00000000
-> start = 0x80000000
-> size = 0x20000000
eth0name = FEC1
ethaddr = (not set)
current eth = FEC1
ip_addr =
baudrate = 115200 bps
TLB addr = 0x9FFF0000
relocaddr = 0x9FF48000
reloc off = 0x18748000
irq_sp = 0x9EF45EA0
sp start = 0x9EF45E90
FB base = 0x00000000
1.2. printenv命令：用于输出环境变量信息
=> printenv
baudrate=115200
board_name=EVK
board_rev=14X14
boot_fdt=try
bootargs=console=ttymxc0,115200 root=/dev/nfs ip=dhcp nfsroot=:,v3,tcp
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=3
bootscript=echo Running bootscript from mmc ...; source
console=ttymxc0
ethact=FEC1
ethprime=FEC
fdt_addr=0x83000000
fdt_file=imx6ull-14x14-emmc-4.3-480x272-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;
get_cmd=dhcp
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 ${boot_fdt} = try; then bootz; else echo WARN: Cannot load the DT; fi; fi; else bootz; fi;
mmcdev=0
mmcpart=1
mmcroot=/dev/mmcblk0p2 rootwait rw
netargs=setenv bootargs console=${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-4.3-480x272
script=boot.scr
splashimage=0x88000000
splashpos=m,m
Environment size: 2624/8188 bytes
1.3. version命令：用于查看 uboot 的版本号
U-Boot 2016.03 (Dec 08 2019 - 19:34:40 +0800)
arm-linux-gnueabihf-gcc (Linaro GCC 7.4-2019.02) 7.4.1 20181213 [linaro-7.4-2019.02 revision 56ec6f6b99cc167ff0c2f8e1a2eed33b1edc85d4]
GNU ld (Linaro_Binutils-2019.02) 2.28.2.20170706
- 环境变量操作命令
2.1. setenv命令：设置环境变量
2.2. saveenv命令：保存环境变量
=> ? setenv
setenv - set environment variables
Usage:
setenv [-f] name value ...
- [forcibly] set environment variable 'name' to 'value ...'
setenv [-f] name
- [forcibly] delete environment variable 'name'
先查看一下其应用信息，即通过环境变量的名称对此变量设置相应的值，[-f]是强制设置参数，属可选项。
设置启动延时
=> setenv bootdelay 5
=> saveenv
Saving Environment to MMC...
Writing to MMC(0)... done
设置bootcmd信息
=> setenv bootcmd 'console=ttymxc0,115200 root=/dev/mmcblk1p2 rootwait rw'
=> saveenv
Saving Environment to MMC...
Writing to MMC(0)... done
- 内存操作命令
3.1. md命令：用于显示内存值，格式如下
=> ? md
md - memory display
Usage:
md [.b, .w, .l] address [# of objects]
如以几种格式显示内存指令：
=> md.b 87800000 10
87800000: b8 00 00 ea 14 f0 9f e5 14 f0 9f e5 14 f0 9f e5
=> md.w 87800000 10
87800000: 00b8 ea00 f014 e59f f014 e59f f014 e59f
87800010: f014 e59f f014 e59f f014 e59f f014 e59f
=> md.l 87800000 10
87800000: ea0000b8 e59ff014 e59ff014 e59ff014
87800010: e59ff014 e59ff014 e59ff014 e59ff014
87800020: 87800060 878000c0 87800120 87800180
87800030: 878001e0 87800240 878002a0 deadbeef
3.2 nm命令：用于修改指定地址的内存值，命令格式如下：
=> ? nm
nm - memory modify (constant address)
Usage:
nm [.b, .w, .l] address
以下以长整型显示并修改0x80000000地址的内容
=> md.l 80000000 1
80000000: ffffffff ....
=> nm.l 80000000
80000000: ffffffff ? 12345678
80000000: 12345678 ? q
=> md.l 80000000 1
80000000: 12345678
3.3. mm命令：修改指定地址的内存值，其地址会自增。其指令格式如下
=> ? mm
mm - memory modify (auto-incrementing address)
Usage:
mm [.b, .w, .l] address
以下以长整型显示并修改0x80000000起始地址的4个字内容
=> mm.l 80000000
80000000: 12345678 ?
80000004: ffffffff ? 87654321
80000008: ffffffff ? 34127856
8000000c: ffffffff ? 78563412
80000010: ffffffff ? q
=> md.l 80000000 4
80000000: 12345678 87654321 34127856 78563412
3.4. mw命令，用于使用一个指定的数据填充一段内存，命令格式如下
=> ? mw
mw - memory write (fill)
Usage:
mw [.b, .w, .l] address value [count]
使用.l 格式将以 0X80000000 为起始地址的 4 个
内存块(4 * 4=16 字节)填充为 0x55AA55AA
=> mw.l 80000000 0x55AA55AA 4
=> md.l 80000000 4
80000000: 55aa55aa 55aa55aa 55aa55aa 55aa55aa
3.5. cp命令，用于将数据从一段存储空间拷贝到另一段存储空间，命令格式如下
=> ? cp
cp - memory copy
Usage:
cp [.b, .w, .l] source target count
使用.l 格式将 0x80000000 处的地址拷贝到 0X80000100 处，长度为 4 个
=> cp.l 80000000 80000100 4
=> md.l 80000000 4
80000000: 55aa55aa 55aa55aa 55aa55aa 55aa55aa .U.U.U.U.U.U.U.U
=> md.l 80000100 4
80000100: 55aa55aa 55aa55aa 55aa55aa 55aa55aa
3.6 cmp命令，用于比较两段内存的数据是否相等，命令格式如下
=> ? cmp
cmp - memory compare
Usage:
cmp [.b, .w, .l] addr1 addr2 count
这里以,l格式比较0x80000000起始地址与0x80000100起始地址的6个存储空间是否相等
=> cmp.l 80000000 80000100 6
Total of 6 word(s) were the same
- 网络操作命令
4.1 nfs命令，使用NFS协议通过网络加载镜像文件到指定地址。
命令格式如下：
=> ? nfs
nfs - boot image via network using NFS protocol
Usage:
nfs [loadAddress] [[hostIPaddr:]bootfilename]
这里将配置好的zImage镜像文件加载到0x80800000地址，执行卡壳了，查了几天了，没有找到原因（有朋友说需要把nfs服务版本改为v2的就可以了，还没有验证）。
=> nfs 80800000 192.168.1.55:/home/glen/linux/nfs/zImage
FEC1 Waiting for PHY auto negotiation to complete... done
Using FEC1 device
File transfer via NFS from server 192.168.1.55; our IP address is 192.168.1.56
Filename '/home/glen/linux/nfs/zImage'.
Load address: 0x80800000
Loading: *** ERROR: File lookup fail
T T T T T T
4.2 tftp命令，使用TFTP协议通过网络加载镜像文件到指定地址。
命令格式如下：
=> ? tftp
tftpboot - boot image via network using TFTP protocol
Usage:
tftpboot [loadAddress] [[hostIPaddr:]bootfilename]
linux主机需要安装tftp服务，并且进行相应地配置，这里就不写了。这里将配置好的zImage镜像文件加载到0x80800000地址。
=> tftp 80800000 zImage
Using FEC1 device
TFTP from server 192.168.1.55; our IP address is 192.168.1.56
Filename 'zImage'.
Load address: 0x80800000
Loading: #################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#######
1.7 MiB/s
done
Bytes transferred = 6777096 (676908 hex)
- EMMC操作命令
5.1 mmc info命令，用于输出当前选中的mmc info信息。
执行命令如下：
=> mmc info
Device: FSL_SDHC
Manufacturer ID: 15
OEM: 100
Name: 8GTF4
Tran Speed: 52000000
Rd Block Len: 512
MMC version 4.0
High Capacity: Yes
Capacity: 7.3 GiB
Bus Width: 8-bit
Erase Group Size: 512 KiB
5.2 mmc rescan命令，用于扫描目标板上所有的MMC设备，包括EMMC和SD卡。
执行命令如下，执行后无回复信息。
=> mmc rescan
5.3 mmc list命令，列出目标板上所有的MMC设备。
执行命令如下：
=> mmc list
FSL_SDHC: 0
FSL_SDHC: 1 (eMMC)
注：FSL_SDHC: 0是目标板的SD卡，FSL_SDHC: 1(eMMC)是核心板上焊接的8GiB的emmc存储芯片。
5.4 mmc dev命令，用于切换当前MMC设备。
执行命令如下：
=> mmc dev
switch to partitions #0, OK
mmc1(part 0) is current device
=> mmc dev 0
switch to partitions #0, OK
mmc0 is current device
=> mmc dev 1
switch to partitions #0, OK
mmc1(part 0) is current device
5.4 mmc part命令，用于查看当前MMC设备的分区情况。
执行命令如下：
=> mmc part
Partition Map for MMC device 1 -- Partition Type: DOS
Part Start Sector Num Sectors UUID Type
1 20480 262144 06478912-01 0c
2 282624 14987264 06478912-02 83
注：这里显示emmc存储芯片有两个分区。
5.6 mmc read命令，用于读到mmc设备的数据，命令格式如下：
mmc read addr blk# cnt
addr 是数据读取到 DRAM 中的地址， blk 是要读取的块起始地址(十六进制)，一个块是 512字节，这里的块和扇区是一个意思，在 MMC 设备中我们通常说扇区， cnt 是要读取的块数量(十六进制)。比如从 EMMC 的第 1536(0x600)个块开始，读取 16(0x10)个块的数据到 DRAM 的0x80800000 地址处，命令如下：
=> mmc dev 1 0
switch to partitions #0, OK
mmc1(part 0) is current device
=> mmc read 80800000 600 10
MMC read: dev # 1, block # 1536, count 16 ... 16 blocks read: OK
这里切换到emmc的第0个分区，并读取第0x600个起始块的0x10个块的内容到0x80800000地址处。
=> md.b 80800000 2000
80800000: 08 45 0d 8b 62 61 75 64 72 61 74 65 3d 31 31 35 .E..baudrate=115
80800010: 32 30 30 00 62 6f 61 72 64 5f 6e 61 6d 65 3d 45 200.board_name=E
80800020: 56 4b 00 62 6f 61 72 64 5f 72 65 76 3d 31 34 58 VK.board_rev=14X
80800030: 31 34 00 62 6f 6f 74 5f 66 64 74 3d 74 72 79 00 14.boot_fdt=try.
80800040: 62 6f 6f 74 63 6d 64 3d 72 75 6e 20 66 69 6e 64 bootcmd=run find
80800050: 66 64 74 3b 6d 6d 63 20 64 65 76 20 24 7b 6d 6d fdt;mmc dev ${mm
80800060: 63 64 65 76 7d 3b 6d 6d 63 20 64 65 76 20 24 7b cdev};mmc dev ${
80800070: 6d 6d 63 64 65 76 7d 3b 20 69 66 20 6d 6d 63 20 mmcdev}; if mmc
80800080: 72 65 73 63 61 6e 3b 20 74 68 65 6e 20 69 66 20 rescan; then if
80800090: 72 75 6e 20 6c 6f 61 64 62 6f 6f 74 73 63 72 69 run loadbootscri
808000a0: 70 74 3b 20 74 68 65 6e 20 72 75 6e 20 62 6f 6f pt; then run boo
808000b0: 74 73 63 72 69 70 74 3b 20 65 6c 73 65 20 69 66 tscript; else if
808000c0: 20 72 75 6e 20 6c 6f 61 64 69 6d 61 67 65 3b 20 run loadimage;
808000d0: 74 68 65 6e 20 72 75 6e 20 6d 6d 63 62 6f 6f 74 then run mmcboot
808000e0: 3b 20 65 6c 73 65 20 72 75 6e 20 6e 65 74 62 6f ; else run netbo
808000f0: 6f 74 3b 20 66 69 3b 20 66 69 3b 20 65 6c 73 65 ot; fi; fi; else
80800100: 20 72 75 6e 20 6e 65 74 62 6f 6f 74 3b 20 66 69 run netboot; fi
80800110: 00 62 6f 6f 74 63 6d 64 5f 6d 66 67 3d 72 75 6e .bootcmd_mfg=run
80800120: 20 6d 66 67 74 6f 6f 6c 5f 61 72 67 73 3b 62 6f mfgtool_args;bo
80800130: 6f 74 7a 20 24 7b 6c 6f 61 64 61 64 64 72 7d 20 otz ${loadaddr}
80800140: 24 7b 69 6e 69 74 72 64 5f 61 64 64 72 7d 20 24 ${initrd_addr} $
80800150: 7b 66 64 74 5f 61 64 64 72 7d 3b 00 62 6f 6f 74 {fdt_addr};.boot
80800160: 64 65 6c 61 79 3d 33 00 62 6f 6f 74 73 63 72 69 delay=3.bootscri
80800170: 70 74 3d 65 63 68 6f 20 52 75 6e 6e 69 6e 67 20 pt=echo Running
80800180: 62 6f 6f 74 73 63 72 69 70 74 20 66 72 6f 6d 20 bootscript from
80800190: 6d 6d 63 20 2e 2e 2e 3b 20 73 6f 75 72 63 65 00 mmc ...; source.
808001a0: 63 6f 6e 73 6f 6c 65 3d 74 74 79 6d 78 63 30 00 console=ttymxc0.
808001b0: 65 74 68 61 63 74 3d 46 45 43 31 00 65 74 68 61 ethact=FEC1.etha
808001c0: 64 64 72 3d 30 30 3a 30 34 3a 33 35 3a 35 36 3a ddr=00:04:35:56:
808001d0: 39 46 3a 33 33 00 65 74 68 70 72 69 6d 65 3d 46 9F:33.ethprime=F
808001e0: 45 43 00 66 64 74 5f 61 64 64 72 3d 30 78 38 33 EC.fdt_addr=0x83
808001f0: 30 30 30 30 30 30 00 66 64 74 5f 66 69 6c 65 3d 000000.fdt_file=
80800200: 69 6d 78 36 75 6c 6c 2d 31 34 78 31 34 2d 65 6d imx6ull-14x14-em
80800210: 6d 63 2d 37 2d 31 30 32 34 78 36 30 30 2d 63 2e mc-7-1024x600-c.
80800220: 64 74 62 00 66 64 74 5f 68 69 67 68 3d 30 78 66 dtb.fdt_high=0xf
80800230: 66 66 66 66 66 66 66 00 66 69 6e 64 66 64 74 3d fffffff.findfdt=
80800240: 69 66 20 74 65 73 74 20 24 66 64 74 5f 66 69 6c if test $fdt_fil
80800250: 65 20 3d 20 75 6e 64 65 66 69 6e 65 64 3b 20 74 e = undefined; t
80800260: 68 65 6e 20 69 66 20 74 65 73 74 20 24 62 6f 61 hen if test $boa
80800270: 72 64 5f 6e 61 6d 65 20 3d 20 45 56 4b 20 26 26 rd_name = EVK &&
80800280: 20 74 65 73 74 20 24 62 6f 61 72 64 5f 72 65 76 test $board_rev
80800290: 20 3d 20 39 58 39 3b 20 74 68 65 6e 20 73 65 74 = 9X9; then set
808002a0: 65 6e 76 20 66 64 74 5f 66 69 6c 65 20 69 6d 78 env fdt_file imx
808002b0: 36 75 6c 6c 2d 39 78 39 2d 65 76 6b 2e 64 74 62 6ull-9x9-evk.dtb
808002c0: 3b 20 66 69 3b 20 69 66 20 74 65 73 74 20 24 62 ; fi; if test $b
808002d0: 6f 61 72 64 5f 6e 61 6d 65 20 3d 20 45 56 4b 20 oard_name = EVK
808002e0: 26 26 20 74 65 73 74 20 24 62 6f 61 72 64 5f 72 && test $board_r
808002f0: 65 76 20 3d 20 31 34 58 31 34 3b 20 74 68 65 6e ev = 14X14; then
80800300: 20 73 65 74 65 6e 76 20 66 64 74 5f 66 69 6c 65 setenv fdt_file
80800310: 20 69 6d 78 36 75 6c 6c 2d 31 34 78 31 34 2d 65 imx6ull-14x14-e
80800320: 76 6b 2e 64 74 62 3b 20 66 69 3b 20 69 66 20 74 vk.dtb; fi; if t
80800330: 65 73 74 20 24 66 64 74 5f 66 69 6c 65 20 3d 20 est $fdt_file =
80800340: 75 6e 64 65 66 69 6e 65 64 3b 20 74 68 65 6e 20 undefined; then
80800350: 65 63 68 6f 20 57 41 52 4e 49 4e 47 3a 20 43 6f echo WARNING: Co
80800360: 75 6c 64 20 6e 6f 74 20 64 65 74 65 72 6d 69 6e uld not determin
80800370: 65 20 64 74 62 20 74 6f 20 75 73 65 3b 20 66 69 e dtb to use; fi
80800380: 3b 20 66 69 3b 00 67 61 74 65 77 61 79 69 70 3d ; fi;.gatewayip=
80800390: 31 39 32 2e 31 36 38 2e 31 2e 31 00 69 6d 61 67 192.168.1.1.imag
808003a0: 65 3d 7a 49 6d 61 67 65 00 69 6e 69 74 72 64 5f e=zImage.initrd_
808003b0: 61 64 64 72 3d 30 78 38 33 38 30 30 30 30 30 00 addr=0x83800000.
808003c0: 69 6e 69 74 72 64 5f 68 69 67 68 3d 30 78 66 66 initrd_high=0xff
808003d0: 66 66 66 66 66 66 00 69 70 5f 64 79 6e 3d 79 65 ffffff.ip_dyn=ye
808003e0: 73 00 69 70 61 64 64 72 3d 31 39 32 2e 31 36 38 s.ipaddr=192.168
808003f0: 2e 31 2e 35 36 00 6c 6f 61 64 61 64 64 72 3d 30 .1.56.loadaddr=0
80800400: 78 38 30 38 30 30 30 30 30 00 6c 6f 61 64 62 6f x80800000.loadbo
80800410: 6f 74 73 63 72 69 70 74 3d 66 61 74 6c 6f 61 64 otscript=fatload
80800420: 20 6d 6d 63 20 24 7b 6d 6d 63 64 65 76 7d 3a 24 mmc ${mmcdev}:$
80800430: 7b 6d 6d 63 70 61 72 74 7d 20 24 7b 6c 6f 61 64 {mmcpart} ${load
80800440: 61 64 64 72 7d 20 24 7b 73 63 72 69 70 74 7d 3b addr} ${script};
80800450: 00 6c 6f 61 64 66 64 74 3d 66 61 74 6c 6f 61 64 .loadfdt=fatload
80800460: 20 6d 6d 63 20 24 7b 6d 6d 63 64 65 76 7d 3a 24 mmc ${mmcdev}:$
80800470: 7b 6d 6d 63 70 61 72 74 7d 20 24 7b 66 64 74 5f {mmcpart} ${fdt_
80800480: 61 64 64 72 7d 20 24 7b 66 64 74 5f 66 69 6c 65 addr} ${fdt_file
80800490: 7d 00 6c 6f 61 64 69 6d 61 67 65 3d 66 61 74 6c }.loadimage=fatl
808004a0: 6f 61 64 20 6d 6d 63 20 24 7b 6d 6d 63 64 65 76 oad mmc ${mmcdev
808004b0: 7d 3a 24 7b 6d 6d 63 70 61 72 74 7d 20 24 7b 6c }:${mmcpart} ${l
808004c0: 6f 61 64 61 64 64 72 7d 20 24 7b 69 6d 61 67 65 oadaddr} ${image
808004d0: 7d 00 6c 6f 67 6f 5f 66 69 6c 65 3d 61 6c 69 65 }.logo_file=alie
808004e0: 6e 74 65 6b 2e 62 6d 70 00 6d 66 67 74 6f 6f 6c ntek.bmp.mfgtool
808004f0: 5f 61 72 67 73 3d 73 65 74 65 6e 76 20 62 6f 6f _args=setenv boo
80800500: 74 61 72 67 73 20 63 6f 6e 73 6f 6c 65 3d 24 7b targs console=${
80800510: 63 6f 6e 73 6f 6c 65 7d 2c 24 7b 62 61 75 64 72 console},${baudr
80800520: 61 74 65 7d 20 72 64 69 6e 69 74 3d 2f 6c 69 6e ate} rdinit=/lin
80800530: 75 78 72 63 20 67 5f 6d 61 73 73 5f 73 74 6f 72 uxrc g_mass_stor
80800540: 61 67 65 2e 73 74 61 6c 6c 3d 30 20 67 5f 6d 61 age.stall=0 g_ma
80800550: 73 73 5f 73 74 6f 72 61 67 65 2e 72 65 6d 6f 76 ss_storage.remov
80800560: 61 62 6c 65 3d 31 20 67 5f 6d 61 73 73 5f 73 74 able=1 g_mass_st
80800570: 6f 72 61 67 65 2e 66 69 6c 65 3d 2f 66 61 74 20 orage.file=/fat
80800580: 67 5f 6d 61 73 73 5f 73 74 6f 72 61 67 65 2e 72 g_mass_storage.r
80800590: 6f 3d 31 20 67 5f 6d 61 73 73 5f 73 74 6f 72 61 o=1 g_mass_stora
808005a0: 67 65 2e 69 64 56 65 6e 64 6f 72 3d 30 78 30 36 ge.idVendor=0x06
808005b0: 36 46 20 67 5f 6d 61 73 73 5f 73 74 6f 72 61 67 6F g_mass_storag
808005c0: 65 2e 69 64 50 72 6f 64 75 63 74 3d 30 78 33 37 e.idProduct=0x37
808005d0: 46 46 20 67 5f 6d 61 73 73 5f 73 74 6f 72 61 67 FF g_mass_storag
808005e0: 65 2e 69 53 65 72 69 61 6c 4e 75 6d 62 65 72 3d e.iSerialNumber=
808005f0: 22 22 20 63 6c 6b 5f 69 67 6e 6f 72 65 5f 75 6e "" clk_ignore_un
80800600: 75 73 65 64 20 00 6d 6d 63 61 72 67 73 3d 73 65 used .mmcargs=se
80800610: 74 65 6e 76 20 62 6f 6f 74 61 72 67 73 20 63 6f tenv bootargs co
80800620: 6e 73 6f 6c 65 3d 24 7b 63 6f 6e 73 6f 6c 65 7d nsole=${console}
80800630: 2c 24 7b 62 61 75 64 72 61 74 65 7d 20 72 6f 6f ,${baudrate} roo
80800640: 74 3d 24 7b 6d 6d 63 72 6f 6f 74 7d 00 6d 6d 63 t=${mmcroot}.mmc
80800650: 61 75 74 6f 64 65 74 65 63 74 3d 79 65 73 00 6d autodetect=yes.m
80800660: 6d 63 62 6f 6f 74 3d 65 63 68 6f 20 42 6f 6f 74 mcboot=echo Boot
80800670: 69 6e 67 20 66 72 6f 6d 20 6d 6d 63 20 2e 2e 2e ing from mmc ...
80800680: 3b 20 72 75 6e 20 6d 6d 63 61 72 67 73 3b 20 69 ; run mmcargs; i
80800690: 66 20 74 65 73 74 20 24 7b 62 6f 6f 74 5f 66 64 f test ${boot_fd
808006a0: 74 7d 20 3d 20 79 65 73 20 7c 7c 20 74 65 73 74 t} = yes || test
808006b0: 20 24 7b 62 6f 6f 74 5f 66 64 74 7d 20 3d 20 74 ${boot_fdt} = t
808006c0: 72 79 3b 20 74 68 65 6e 20 69 66 20 72 75 6e 20 ry; then if run
808006d0: 6c 6f 61 64 66 64 74 3b 20 74 68 65 6e 20 62 6f loadfdt; then bo
808006e0: 6f 74 7a 20 24 7b 6c 6f 61 64 61 64 64 72 7d 20 otz ${loadaddr}
808006f0: 2d 20 24 7b 66 64 74 5f 61 64 64 72 7d 3b 20 65 - ${fdt_addr}; e
80800700: 6c 73 65 20 69 66 20 74 65 73 74 20 24 7b 62 6f lse if test ${bo
80800710: 6f 74 5f 66 64 74 7d 20 3d 20 74 72 79 3b 20 74 ot_fdt} = try; t
80800720: 68 65 6e 20 62 6f 6f 74 7a 3b 20 65 6c 73 65 20 hen bootz; else
80800730: 65 63 68 6f 20 57 41 52 4e 3a 20 43 61 6e 6e 6f echo WARN: Canno
80800740: 74 20 6c 6f 61 64 20 74 68 65 20 44 54 3b 20 66 t load the DT; f
80800750: 69 3b 20 66 69 3b 20 65 6c 73 65 20 62 6f 6f 74 i; fi; else boot
80800760: 7a 3b 20 66 69 3b 00 6d 6d 63 64 65 76 3d 31 00 z; fi;.mmcdev=1.
80800770: 6d 6d 63 70 61 72 74 3d 31 00 6d 6d 63 72 6f 6f mmcpart=1.mmcroo
80800780: 74 3d 2f 64 65 76 2f 6d 6d 63 62 6c 6b 31 70 32 t=/dev/mmcblk1p2
80800790: 20 72 6f 6f 74 77 61 69 74 20 72 77 00 6e 65 74 rootwait rw.net
808007a0: 61 72 67 73 3d 73 65 74 65 6e 76 20 62 6f 6f 74 args=setenv boot
808007b0: 61 72 67 73 20 63 6f 6e 73 6f 6c 65 3d 24 7b 63 args console=${c
808007c0: 6f 6e 73 6f 6c 65 7d 2c 24 7b 62 61 75 64 72 61 onsole},${baudra
808007d0: 74 65 7d 20 72 6f 6f 74 3d 2f 64 65 76 2f 6e 66 te} root=/dev/nf
808007e0: 73 20 69 70 3d 64 68 63 70 20 6e 66 73 72 6f 6f s ip=dhcp nfsroo
808007f0: 74 3d 24 7b 73 65 72 76 65 72 69 70 7d 3a 24 7b t=${serverip}:${
80800800: 6e 66 73 72 6f 6f 74 7d 2c 76 33 2c 74 63 70 00 nfsroot},v3,tcp.
80800810: 6e 65 74 62 6f 6f 74 3d 65 63 68 6f 20 42 6f 6f netboot=echo Boo
80800820: 74 69 6e 67 20 66 72 6f 6d 20 6e 65 74 20 2e 2e ting from net ..
80800830: 2e 3b 20 72 75 6e 20 6e 65 74 61 72 67 73 3b 20 .; run netargs;
80800840: 69 66 20 74 65 73 74 20 24 7b 69 70 5f 64 79 6e if test ${ip_dyn
80800850: 7d 20 3d 20 79 65 73 3b 20 74 68 65 6e 20 73 65 } = yes; then se
80800860: 74 65 6e 76 20 67 65 74 5f 63 6d 64 20 64 68 63 tenv get_cmd dhc
80800870: 70 3b 20 65 6c 73 65 20 73 65 74 65 6e 76 20 67 p; else setenv g
80800880: 65 74 5f 63 6d 64 20 74 66 74 70 3b 20 66 69 3b et_cmd tftp; fi;
80800890: 20 24 7b 67 65 74 5f 63 6d 64 7d 20 24 7b 69 6d ${get_cmd} ${im
808008a0: 61 67 65 7d 3b 20 69 66 20 74 65 73 74 20 24 7b age}; if test ${
808008b0: 62 6f 6f 74 5f 66 64 74 7d 20 3d 20 79 65 73 20 boot_fdt} = yes
808008c0: 7c 7c 20 74 65 73 74 20 24 7b 62 6f 6f 74 5f 66 || test ${boot_f
808008d0: 64 74 7d 20 3d 20 74 72 79 3b 20 74 68 65 6e 20 dt} = try; then
808008e0: 69 66 20 24 7b 67 65 74 5f 63 6d 64 7d 20 24 7b if ${get_cmd} ${
808008f0: 66 64 74 5f 61 64 64 72 7d 20 24 7b 66 64 74 5f fdt_addr} ${fdt_
80800900: 66 69 6c 65 7d 3b 20 74 68 65 6e 20 62 6f 6f 74 file}; then boot
80800910: 7a 20 24 7b 6c 6f 61 64 61 64 64 72 7d 20 2d 20 z ${loadaddr} -
80800920: 24 7b 66 64 74 5f 61 64 64 72 7d 3b 20 65 6c 73 ${fdt_addr}; els
80800930: 65 20 69 66 20 74 65 73 74 20 24 7b 62 6f 6f 74 e if test ${boot
80800940: 5f 66 64 74 7d 20 3d 20 74 72 79 3b 20 74 68 65 _fdt} = try; the
80800950: 6e 20 62 6f 6f 74 7a 3b 20 65 6c 73 65 20 65 63 n bootz; else ec
80800960: 68 6f 20 57 41 52 4e 3a 20 43 61 6e 6e 6f 74 20 ho WARN: Cannot
80800970: 6c 6f 61 64 20 74 68 65 20 44 54 3b 20 66 69 3b load the DT; fi;
80800980: 20 66 69 3b 20 65 6c 73 65 20 62 6f 6f 74 7a 3b fi; else bootz;
80800990: 20 66 69 3b 00 6e 65 74 6d 61 73 6b 3d 32 35 35 fi;.netmask=255
808009a0: 2e 32 35 35 2e 32 35 35 2e 30 00 70 61 6e 65 6c .255.255.0.panel
808009b0: 3d 41 54 4b 2d 4c 43 44 2d 37 2d 31 30 32 34 78 =ATK-LCD-7-1024x
808009c0: 36 30 30 00 73 63 72 69 70 74 3d 62 6f 6f 74 2e 600.script=boot.
808009d0: 73 63 72 00 73 65 72 76 65 72 69 70 3d 31 39 32 scr.serverip=192
808009e0: 2e 31 36 38 2e 31 2e 35 35 00 73 70 6c 61 73 68 .168.1.55.splash
808009f0: 69 6d 61 67 65 3d 30 78 38 38 30 30 30 30 30 30 image=0x88000000
80800a00: 00 73 70 6c 61 73 68 70 6f 73 3d 6d 2c 6d 00 00 .splashpos=m,m..
80800a10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
......
这里显示出读取的内容，可以看出，这就是uboot的环境变量信息。
5.7 mmc write命令，将数据写到MMC设备里面。命令格式如下：
mmc write addr blk# cnt
addr 是要写入 MMC 中的数据在 DRAM 中的起始地址， blk 是要写入 MMC 的块起始地址(十六进制)， cnt 是要写入的块大小，一个块为 512 字节。我们可以使用命令“mmc write”来升级 uboot，也就是在 uboot 中更新 uboot。这里要用到 nfs 或者 tftp 命令，通过 nfs 或者 tftp 命令将新的 u-boot.bin 下载到开发板的 DRAM 中，然后再使用命令“mmc write”将其写入到 MMC设备中。
=> mmc dev 0
switch to partitions #0, OK
mmc0 is current device
切换到SD卡，查看版本号
=> version
U-Boot 2016.03-g9bd38ef (Oct 23 2019 - 09:31:47 +0800)
arm-poky-linux-gnueabi-gcc (GCC) 5.3.0
GNU ld (GNU Binutils) 2.26.0.20160214
加载重新编译的u-boot文件，
=> tftp 80800000 u-boot.imx
Using FEC1 device
TFTP from server 192.168.1.55; our IP address is 192.168.1.56
Filename 'u-boot.imx'.
Load address: 0x80800000
Loading: #############################
1.7 MiB/s
done
Bytes transferred = 424960 (67c00 hex)
切换到SD卡的0分区，并将第2个起始块开始的33E（424960 /512=830=0x33E, 424960为新编译的u-boot.imx文件的大小）个块写入到SD当中。
=> mmc dev 0 0
switch to partitions #0, OK
mmc0 is current device
=> mmc write 80800000 2 33E
MMC write: dev # 0, block # 2, count 814 ... 814 blocks written: OK
将目标板设置为SD卡启动，重新启动，显示的启动信息为当前编译日期。
=>
U-Boot 2016.03 (Dec 15 2019 - 23:45:46 +0800)
CPU: Freescale i.MX6ULL rev1.1 69 MHz (running at 396 MHz)
CPU: Industrial temperature grade (-40C to 105C) at 59C
Reset cause: POR
Board: MX6ULL 14x14 EVK
I2C: ready
DRAM: 512 MiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
Display: ATK-LCD-7-1024x600 (1024x600)
Video: 1024x600x24
reading alientek.bmp
** Unable to read file alientek.bmp **
Error: no valid bmp image at 88000000
In: serial
Out: serial
Err: serial
switch to partitions #0, OK
mmc1(part 0) is current device
Net: FEC1
Normal Boot
Hit any key to stop autoboot: 0
- FAT格式文件系统操作命令
6.1 fatinfo命令，用于输出指定介质分区的文件系统相关信息。命令格式如下：
=> ? fatinfo
fatinfo - print information about filesystem
Usage:
fatinfo []
- print information about filesystem from 'dev' on 'interface'
以下是我的目标板两个MMC介质的分区信息
=> fatinfo mmc 1:1
Interface: MMC
Device 1: Vendor: Man 000015 Snr f565de41 Rev: 0.6 Prod: 8GTF4R
Type: Removable Hard Disk
Capacity: 7456.0 MB = 7.2 GB (15269888 x 512)
Filesystem: FAT32 "NO NAME "
=> fatinfo mmc 0:1
Interface: MMC
Device 0: Vendor: Man 000003 Snr 511f1b01 Rev: 6.9 Prod: SC16G Type: Removable Hard Disk
Capacity: 15193.5 MB = 14.8 GB (31116288 x 512)
Filesystem: FAT32 "NO NAME "
6.2 fatls命令，用于查询 FAT文件系统设备介质根目录和文件信息，命令格式如下：
=> ? fatls
fatls - list files in a directory (default /)
Usage:
fatls [] [directory]
- list files from 'dev' on 'interface' in a 'directory'
这里显示我的目标板第1个MMC设备（eMMC存储芯片)的第1个分区的信息
=> fatls mmc 1:1
6777096 zimage
38270 imx6ull-14x14-emmc-4.3-480x272-c.dtb
38270 imx6ull-14x14-emmc-4.3-800x480-c.dtb
38270 imx6ull-14x14-emmc-7-800x480-c.dtb
38270 imx6ull-14x14-emmc-7-1024x600-c.dtb
38270 imx6ull-14x14-emmc-10.1-1280x800-c.dtb
6 file(s), 0 dir(s)
6.3 fstype命令，查看存储介质某个分区的文件系统，命令格式如下：
=> ? fstype
fstype - Look up a filesystem type
Usage:
fstype :
- print filesystem type
fstype :
- set environment variable to filesystem type
这里显示目标板的几个分区的文件系统格式
=> fstype mmc 1:0
Failed to mount ext2 filesystem...
** Unrecognized filesystem type **
=> fstype mmc 1:1
fat
=> fstype mmc 1:2
ext4
=> fstype mmc 0:0
Failed to mount ext2 filesystem...
** Unrecognized filesystem type **
=> fstype mmc 0:1
fat
=> fstype mmc 0:2
** Invalid partition 2 **
6.4 fatload命令，用于将指定的文件读取RAM中，命令格式如下：
=> ? fatload
fatload - load binary file from a dos filesystem
Usage:
fatload [ [ [ [bytes [pos]]]]]
- Load binary file 'filename' from 'dev' on 'interface'
to address 'addr' from dos filesystem.
'pos' gives the file position to start loading from.
If 'pos' is omitted, 0 is used. 'pos' requires 'bytes'.
'bytes' gives the size to load. If 'bytes' is 0 or omitted,
the load stops on end of file.
If either 'pos' or 'bytes' are not aligned to
ARCH_DMA_MINALIGN then a misaligned buffer warning will
be printed and performance will suffer for the load.
这里把第1个MMC设备的第1个分区的zImage文件读取到0x80800000地址
=> fatload mmc 1:1 80800000 zImage
reading zImage
6777096 bytes read in 221 ms (29.2 MiB/s)
6.5 fatwrite命令，用于将DRAM中的数据定入到存储介质中。命令格式在我手头的目标板上未查到，以下不作演示了。
=> ? fatwrite
Unknown command 'fatwrite' - try 'help' without arguments for list of all known commands
-
EXT格式文件系统操作命令
uboot有ext2load、 ext2ls、 ext4load、 ext4ls 和 ext4write命令，与fat命令类似，此处不再演示。 -
boot操作命令
8.1 bootz命令，用于启动linux系统镜像文件，其命令格式如下：
=> ? 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
如从RAM（需先把linux系统镜像和设备树加载到RAM中去）启动内核
=> bootz 80800000 - 83000000
Kernel image @ 0x80800000 [ 0x000000 - 0x676908 ]
## Flattened Device Tree blob at 83000000
Booting using the fdt blob at 0x83000000
Using Device Tree in place at 83000000, end 8300c57d
Starting kernel ...
8.2 bootm命令，bootm 和 bootz 功能类似，但是 bootm 用于启动 uImage 镜像文件。
=> ? bootm
bootm - boot application image from memory
Usage:
bootm [addr [arg ...]]
- boot application image stored in memory
passing arguments 'arg ...'; when booting a Linux kernel,
'arg' can be the address of an initrd image
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
Sub-commands to do part of the bootm sequence. The sub-commands must be
issued in the order below (it's ok to not issue all sub-commands):
start [addr [arg ...]]
loados - load OS image
ramdisk - relocate initrd, set env initrd_start/initrd_end
fdt - relocate flat device tree
cmdline - OS specific command line processing/setup
bdt - OS specific bd_t processing
prep - OS specific prep before relocation or go
go - start OS
8.3 boot命令，boot 命令也是用来启动 Linux 系统的，只是 boot 会读取环境变量 bootcmd 来启动 Linux 系统， bootcmd 是一个很重要的环境变量！
=> ? boot
boot - boot default, i.e., run 'bootcmd'
Usage:
boot