内核启动时之所以出现如下的错误，可能是使用的SDK版本不正确，我是从openwrt官方下载的。
[ 0.000000] Kernel panic - not syncing: Failed to find ralink,mt7620a-sysc node
[ 0.000000] ---[ end Kernel panic - not syncing: Failed to find ralink,mt7620a-sysc node到https://github.com/WRTnode/openwrt克隆或下载，通过make menuconfig命令配置我们需要的开发板，依次选择 Target System (Ralink RT288x/RT3xxx)中的Ralink RT288x/RT3xxx及Subtarget (WRTnode 2 series)中的WRTnode 2 series，之后按照之前写的OpenWrt：编译系统、OpenWrt：通过tftp下载程序两篇文章进行编译、烧录。说明一下，我们要下载的文件名为openwrt-ramips-mt7628-wrtnode2p-squashfs-sysupgrade.bin，咨询了官方，问题为使用github上的代码编译后，烧录uImage不能正常启动；ubuntu不能连接路由。
购买的开发板，正常启动时打印如下的日志：
U-Boot 1.1.3 (May 31 2017 - 12:06:08)
Board: Ralink APSoC DRAM: 128 MB
relocate_code Pointer at: 87f60000
flash manufacture id: c2, device id 20 18
find flash: MX25L12805D
============================================
Ralink UBoot Version: 4.3.0.0
--------------------------------------------
ASIC 7628_MP (Port5<->None)
DRAM component: 1024 Mbits DDR, width 16
DRAM bus: 16 bit
Total memory: 128 MBytes
Flash component: SPI Flash
Date:May 31 2017 Time:12:06:08
============================================
icache: sets:512, ways:4, linesz:32 ,total:65536
dcache: sets:256, ways:4, linesz:32 ,total:32768
##### The CPU freq = 575 MHZ ####
estimate memory size =128 Mbytes
RESET MT7628 PHY!!!!!!
Please choose the operation:
1: Load system code to SDRAM via TFTP.
2: Load system code then write to Flash via TFTP.
3: Boot system code via Flash (default).
4: Entr boot command line interface.
7: Load Boot Loader code then write to Flash via Serial.
9: Load Boot Loader code then write to Flash via TFTP.
0
3: System Boot system code via Flash.
## Booting image at bc050000 ...
Image Name: MIPS OpenWrt Linux-3.18.29
Image Type: MIPS Linux Kernel Image (lzma compressed)
Data Size: 1138984 Bytes = 1.1 MB
Load Address: 80000000
Entry Point: 80000000
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK
No initrd
## Transferring control to Linux (at address 80000000) ...
## Giving linux memsize in MB, 128
Starting kernel ...
[ 0.000000] Linux version 3.18.29 (xx@build) (gcc version 4.8.3 (OpenWrt/Linaro GCC 4.8-2014.04 r49363) ) #3 Tue May 23 11:27:46 CST 2017
[ 0.000000] Board has DDR2
[ 0.000000] Analog PMU set to hw control
[ 0.000000] Digital PMU set to hw control
[ 0.000000] SoC Type: MediaTek MT7628AN ver:1 eco:2
[ 0.000000] bootconsole [early0] enabled
[ 0.000000] CPU0 revision is: 00019655 (MIPS 24KEc)
[ 0.000000] MIPS: machine is WRTnode2P
[ 0.000000] Determined physical RAM map:
[ 0.000000] memory: 08000000 @ 00000000 (usable)
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x00000000-0x07ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x00000000-0x07ffffff]
[ 0.000000] Initmem setup node 0 [mem 0x00000000-0x07ffffff]
[ 0.000000] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 32512
[ 0.000000] Kernel command line: console=ttyS0,115200 rootfstype=squashfs,jffs2
[ 0.000000] PID hash table entries: 512 (order: -1, 2048 bytes)
[ 0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.000000] Writing ErrCtl register=0000ba42
[ 0.000000] Readback ErrCtl register=0000ba42
[ 0.000000] Memory: 126340K/131072K available (2514K kernel code, 125K rwdata, 516K rodata, 164K init, 186K bss, 4732K reserved)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] NR_IRQS:256
[ 0.000000] intc: using register map from devicetree
[ 0.000000] CPU Clock: 575MHz
[ 0.000000] clocksource_of_init: no matching clocksources found
[ 0.000000] Calibrating delay loop... 380.92 BogoMIPS (lpj=1904640)
[ 0.060000] pid_max: default: 32768 minimum: 301
[ 0.060000] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.070000] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.070000] pinctrl core: initialized pinctrl subsystem
[ 0.080000] NET: Registered protocol family 16
[ 0.090000] rt2880-pinmux pinctrl: invalid group "jtag" for function "gpio"
[ 0.190000] mt7620-pci 10140000.pcie: Port 0 N_FTS = 1b105000
[ 0.340000] mt7620-pci 10140000.pcie: PCIE0 no card, disable it(RST&CLK)
[ 0.350000] mt7620-pci: probe of 10140000.pcie failed with error -1
[ 0.360000] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.370000] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.370000] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.380000] Switched to clocksource MIPS
[ 0.380000] NET: Registered protocol family 2
[ 0.390000] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.390000] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.400000] TCP: Hash tables configured (established 1024 bind 1024)
[ 0.400000] TCP: reno registered
[ 0.410000] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 0.410000] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 0.420000] NET: Registered protocol family 1
[ 0.430000] futex hash table entries: 256 (order: -1, 3072 bytes)
[ 0.450000] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.450000] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[ 0.470000] msgmni has been set to 246
[ 0.470000] io scheduler noop registered
[ 0.470000] io scheduler deadline registered (default)
[ 0.480000] drivers/phy/phy-ralink-usb.c:ralink_usb_phy_probe[336]
[ 0.490000] drivers/phy/phy-ralink-usb.c:ralink_usb_phy_probe[350]
[ 0.490000] Serial: 8250/16550 driver, 2 ports, IRQ sharing disabled
[ 0.500000] console [ttyS0] disabled
[ 0.500000] 10000c00.uartlite: ttyS0 at MMIO 0x10000c00 (irq = 28, base_baud = 2500000) is a 16550A
[ 0.510000] console [ttyS0] enabled
[ 0.510000] console [ttyS0] enabled
[ 0.520000] bootconsole [early0] disabled
[ 0.520000] bootconsole [early0] disabled
[ 0.530000] 10000d00.uart1: ttyS1 at MMIO 0x10000d00 (irq = 29, base_baud = 2500000) is a 16550A
[ 0.540000] MT7628/7688 SPI Driver By WRTnode Team !
[ 0.540000] spi-mt7621 10000b00.spi: sys_freq: 191666666
[ 0.550000] m25p80 spi32766.0: found mx25l12805d, expected w25q256
[ 0.560000] m25p80 spi32766.0: mx25l12805d (16384 Kbytes)
[ 0.560000] m25p80 spi32766.0: using chunked io
[ 0.570000] 4 ofpart partitions found on MTD device spi32766.0
[ 0.570000] Creating 4 MTD partitions on "spi32766.0":
[ 0.580000] 0x000000000000-0x000000030000 : "u-boot"
[ 0.590000] 0x000000030000-0x000000040000 : "u-boot-env"
[ 0.590000] 0x000000040000-0x000000050000 : "factory"
[ 0.600000] 0x000000050000-0x000002000000 : "firmware"
[ 0.600000] mtd: partition "firmware" extends beyond the end of device "spi32766.0" -- size truncated to 0xfb0000
[ 0.680000] 2 uimage-fw partitions found on MTD device firmware
[ 0.680000] 0x000000050000-0x000000166168 : "kernel"
[ 0.690000] 0x000000166168-0x000001000000 : "rootfs"
[ 0.700000] mtd: device 5 (rootfs) set to be root filesystem
[ 0.700000] 1 squashfs-split partitions found on MTD device rootfs
[ 0.710000] 0x000000950000-0x000001000000 : "rootfs_data"
[ 0.730000] ralink_soc_eth 10100000.ethernet eth0: ralink at 0xb0100000, irq 5
[ 0.730000] mt7621_wdt 10000120.watchdog: Initialized
[ 0.740000] TCP: cubic registered
[ 0.740000] NET: Registered protocol family 17
[ 0.750000] bridge: automatic filtering via arp/ip/ip6tables has been deprecated. Update your scripts to load br_netfilter if you need this.
[ 0.760000] 8021q: 802.1Q VLAN Support v1.8
[ 0.780000] VFS: Mounted root (squashfs filesystem) readonly on device 31:5.
[ 0.790000] Freeing unused kernel memory: 164K (80317000 - 80340000)
[ 2.540000] init: Console is alive
[ 2.540000] init: - watchdog -
[ 5.050000] usbcore: registered new interface driver usbfs
[ 5.060000] usbcore: registered new interface driver hub
[ 5.060000] usbcore: registered new device driver usb
[ 5.110000] SCSI subsystem initialized
[ 5.120000] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 5.130000] ehci-platform: EHCI generic platform driver
[ 5.300000] U2PHY P0 set SRCTRL calibration value: 6
[ 5.300000] ehci-platform 101c0000.ehci: EHCI Host Controller
[ 5.310000] ehci-platform 101c0000.ehci: new USB bus registered, assigned bus number 1
[ 5.310000] ehci-platform 101c0000.ehci: irq 26, io mem 0x101c0000
[ 5.340000] ehci-platform 101c0000.ehci: USB 2.0 started, EHCI 1.00
[ 5.340000] hub 1-0:1.0: USB hub found
[ 5.350000] hub 1-0:1.0: 1 port detected
[ 5.350000] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[ 5.360000] ohci-platform: OHCI generic platform driver
[ 5.370000] ohci-platform 101c1000.ohci: Generic Platform OHCI controller
[ 5.370000] ohci-platform 101c1000.ohci: new USB bus registered, assigned bus number 2
[ 5.380000] ohci-platform 101c1000.ohci: irq 26, io mem 0x101c1000
[ 5.450000] hub 2-0:1.0: USB hub found
[ 5.450000] hub 2-0:1.0: 1 port detected
[ 5.470000] MTK MSDC device init.
[ 5.510000] mtk-sd: MediaTek MT6575 MSDC Driver
[ 5.510000] sdhci: Secure Digital Host Controller Interface driver
[ 5.520000] sdhci: Copyright(c) Pierre Ossman
[ 5.520000] sdhci-pltfm: SDHCI platform and OF driver helper
[ 5.530000] usbcore: registered new interface driver usb-storage
[ 5.600000] init: - preinit -
[ 5.700000] usb 1-1: new high-speed USB device number 2 using ehci-platform
[ 6.460000] rt305x-esw 10110000.esw: link changed 0x00
[ 6.650000] random: mktemp urandom read with 10 bits of entropy available
Press the [f] key and hit [enter] to enter failsafe mode
Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
[ 9.440000] rt305x-esw 10110000.esw: link changed 0x01
[ 9.900000] mount_root: loading kmods from internal overlay
[ 10.590000] jffs2: notice: (354) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref.
[ 10.610000] block: attempting to load /tmp/jffs_cfg/upper/etc/config/fstab
[ 10.620000] block: extroot: not configured
[ 10.760000] jffs2: notice: (351) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref.
[ 11.250000] block: attempting to load /tmp/jffs_cfg/upper/etc/config/fstab
[ 11.260000] block: extroot: not configured
[ 11.270000] mount_root: switching to jffs2 overlay
[ 11.300000] procd: - early -
[ 11.300000] procd: - watchdog -
[ 12.010000] procd: - ubus -
[ 13.020000] procd: - init -
Please press Enter to activate this console.
[ 13.890000] NET: Registered protocol family 10
[ 13.920000] ip6_tables: (C) 2000-2006 Netfilter Core Team
[ 13.930000] Ralink/MTK WiFi EEPROM API Build for MT7620.
[ 13.980000] WRTnode AP Driver version: 4.1.0.0
[ 14.000000] fuse init (API version 7.23)
[ 14.010000] ip_tables: (C) 2000-2006 Netfilter Core Team
[ 14.030000] nf_conntrack version 0.5.0 (1976 buckets, 7904 max)
[ 14.110000] xt_time: kernel timezone is -0000
[ 14.120000] PPP generic driver version 2.4.2
[ 14.130000] NET: Registered protocol family 24
[ 17.540000] rt305x-esw 10110000.esw: link changed 0x00
[ 19.520000] device eth0.1 entered promiscuous mode
[ 19.520000] device eth0 entered promiscuous mode
[ 19.550000] br-lan: port 1(eth0.1) entered forwarding state
[ 19.550000] br-lan: port 1(eth0.1) entered forwarding state
[ 19.910000] EEPROM:Read from [factory] offset 0x0,length 0x400.
[ 20.540000] rt305x-esw 10110000.esw: link changed 0x01
[ 20.850000] usb 1-1: device descriptor read/64, error -145
[ 21.550000] br-lan: port 1(eth0.1) entered forwarding state
[ 23.010000] ch6 bssid=8c:21:0a:96:7b:fc
[ 23.010000] ch11 bssid=ec:26:ca:f4:69:92
[ 23.010000] =====================================================
[ 23.020000] Channel 1 : Dirty = 0, False CCA = 0, Busy Time = 17865, Skip Channel = FALSE
[ 23.030000] Channel 2 : Dirty = 20, False CCA = 0, Busy Time = 61175, Skip Channel = FALSE
[ 23.040000] Channel 3 : Dirty = 24, False CCA = 0, Busy Time = 38100, Skip Channel = FALSE
[ 23.040000] Channel 4 : Dirty = 28, False CCA = 0, Busy Time = 10623, Skip Channel = FALSE
[ 23.050000] Channel 5 : Dirty = 32, False CCA = 0, Busy Time = 11554, Skip Channel = FALSE
[ 23.060000] Channel 6 : Dirty = 80, False CCA = 0, Busy Time = 13158, Skip Channel = FALSE
[ 23.070000] Channel 7 : Dirty = 52, False CCA = 0, Busy Time = 26307, Skip Channel = FALSE
[ 23.080000] Channel 8 : Dirty = 52, False CCA = 0, Busy Time = 25331, Skip Channel = FALSE
[ 23.090000] Channel 9 : Dirty = 52, False CCA = 0, Busy Time = 24797, Skip Channel = FALSE
[ 23.090000] Channel 10 : Dirty = 52, False CCA = 0, Busy Time = 22943, Skip Channel = FALSE
[ 23.100000] Channel 11 : Dirty = 90, False CCA = 0, Busy Time = 21541, Skip Channel = FALSE
[ 23.110000] =====================================================
[ 23.120000] Rule 1 CCA value : Min Dirtiness (Include extension channel) ==> Select Channel 1
[ 23.130000] Min Dirty = 0
[ 23.130000] ExChannel = 0 , 0
[ 23.130000] BW = 20
[ 23.160000] IPv6: ADDRCONF(NETDEV_UP): apcli0: link is not ready
[ 23.960000] IPv6: ADDRCONF(NETDEV_UP): apcli0: link is not ready
[ 26.850000] device ra0 entered promiscuous mode
[ 26.850000] br-lan: port 2(ra0) entered forwarding state
[ 26.860000] br-lan: port 2(ra0) entered forwarding state
[ 28.860000] br-lan: port 2(ra0) entered forwarding state
[ 36.080000] usb 1-1: device descriptor read/64, error -145
[ 36.310000] usb 1-1: new high-speed USB device number 3 using ehci-platform
BusyBox v1.23.2 (2017-03-13 11:09:17 CST) built-in shell (ash)
_______ ________ __
| |.-----.-----.-----.| | | |.----.| |_
| - || _ | -__| || | | || _|| _|
|_______|| __|_____|__|__||________||__| |____|
|__| W I R E L E S S F R E E D O M
-----------------------------------------------------
CHAOS CALMER (Chaos Calmer, r49363)
-----------------------------------------------------
* 1 1/2 oz Gin Shake with a glassful
* 1/4 oz Triple Sec of broken ice and pour
* 3/4 oz Lime Juice unstrained into a goblet.
* 1 1/2 oz Orange Juice
* 1 tsp. Grenadine Syrup
-----------------------------------------------------
root@OpenWrt:/# 
**粗体** _斜体_ [链接](http://example.com) `代码` - 列表 > 引用。你还可以使用@来通知其他用户。