最近因工作需要，目前做nuc970 开发板nfs启动的实验，但是现在nfs挂载不上。
开发板启动给出的错误为
usbcore: registered new interface driver usb-storage
TCP: cubic registered
NET: Registered protocol family 17
can: controller area network core (rev 20120528 abi 9)
NET: Registered protocol family 29
can: raw protocol (rev 20120528)
can: broadcast manager protocol (rev 20120528 t)
can: netlink gateway (rev 20130117) max_hops=1
[color#ff0000]
nuc970-emac0 nuc970-emac0: eth0 is OPENED
IP-Config: Complete:
device=eth0, hwaddr=08:00:27:00:01:92, ipaddr=10.0.20.81, mask=255.255.255.0, gw=10.0.20.254
host=10.0.20.81, domain=, nis-domain=(none)
bootserver=10.0.20.78, rootserver=10.0.20.78, rootpath=
VFS: Unable to mount root fs via NFS, trying floppy.
VFS: Cannot open root device "nfs" or unknown-block(2,0): error -6
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
CPU: 0 PID: 1 Comm: swapper Not tainted 3.10.101 #3
[/color]
Backtrace:
[<c0011f24>] (dump_backtrace+0x0/0x10c) from [<c0012138>] (show_stack+0x18/0x1c)
r6:c03fd8d0 r5:00008000 r4:c03977a8 r3:00000000
[<c0012120>] (show_stack+0x0/0x1c) from [<c031a1c8>] (dump_stack+0x20/0x28)
[<c031a1a8>] (dump_stack+0x0/0x28) from [<c0317db4>] (panic+0xa4/0x1f8)
[<c0317d10>] (panic+0x0/0x1f8) from [<c03e2054>] (mount_block_root+0x1c4/0x270)
r3:00000030 r2:00000000 r1:c3843ea0 r0:c03977a8
r7:c0397810
[<c03e1e90>] (mount_block_root+0x0/0x270) from [<c03e22e8>] (mount_root+0xec/0x114)
[<c03e21fc>] (mount_root+0x0/0x114) from [<c03e2470>] (prepare_namespace+0x160/0x1c0)
r8:c03fd8a8 r7:c043b5a0 r6:c03fd8d0 r5:c03fd8d0 r4:c043b600
[<c03e2310>] (prepare_namespace+0x0/0x1c0) from [<c03e1c48>] (kernel_init_freeable+0x1d8/0x220)
r6:c043b5a0 r5:00000007 r4:c0402114
[<c03e1a70>] (kernel_init_freeable+0x0/0x220) from [<c0317710>] (kernel_init+0x10/0x158)
[<c0317700>] (kernel_init+0x0/0x158) from [<c000ecf8>] (ret_from_fork+0x14/0x3c)
r5:c0317700 r4:00000000开发板的启动命令如下
mem=64M console=ttyS0,115200n8 root=/dev/nfs rw rdinit=/sbin/init mtdparts=nand0:16M(boot)ro,-(rootfs) nfsroot=10.0.20.78:/home/cookie/nuc970bsp/rootfs ip=10.0.20.81:10.0.20.78:10.0.20.254:255.255.255.0::eth0:off内核配置了配置了IP支持，nfs客户端支持，root filesystem on nfs.
开发的Linux主机上配置了nfs，同时再另一台电脑上用虚拟机测试能够正确挂载nfs。
但是目前启动不了。求论坛大神给小弟一点指导。google上查询了很多方法但是都不行。
最近编辑记录 thy442156388 (2018-10-21 22:15:29)
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看错误提示是nfs根文件系统没有挂载上, 现在要排除问题:
1. 确认你的 nfs server 能不能被其它linux挂载上?
2. NUC97x使用别的根文件让系统能进入shell, 手动 mount nfs 文件系统，看是否出错.
那这个和busybox 编译的命令有关系么 ？我再看busybox编译配置的时候，印象中mount有一个选项要配置是否支持nfs挂载。是不是自己制作的别的根文件系统再编译busybox 的时候应该加上这个选项。
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内核系统配置是采用新唐给的linux3.10的内核，然后使用nuc972_defconfig。在这个基础上
取消了General setup--》中的Initial RAM filesystem and RAM disk support ，
配置了Networking support---》中的networking options 中的IP：kernel level autoconfiguration；
File system---》下 network file system nfs client 所有选项
File system---》下 network file system 下的 root file system on nfs
这样的内核配置有问题么 ？
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这个难说， 你不能确认网络没有问题吧？你也不能确定NFS服务器一定没有问题吧?
所以还是按照我前面说的方法，
通过其它根文件系统启动到shell,
1. 设置好NUC97x的ip地址， ping NFS服务器， 可以发现NUC97x网络配置,硬件等有没有问题。
2. 手动 mount NFS 服务器到本地目录, 可以判断服务器是否正常。上面都可以之后再配置 u-boot/kernel的 bootargs，设置一楼那些NFS 根文件系统参数，
这样从NFS启动就问题不大了,
如果有问题，也可以排除很多问题了。
我按你说的做了测试，但是新的问题又来了，我烧写了yaffs2文件系统的方式来启动开发板，但是在yaffs2文件系统下仍然不能够挂在nfs。我在我的另外一台电脑的ubunutu虚拟机中测试是可以挂在nfs的。
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现在yaffs2文件系统的nfs能够挂在上去了，在制作文件系统的时候在busybox中的mount命令配置里，官方给的默认配置mount没有给配置挂载nfs的功能，重新配置制作的文件系统可以挂载nfs，但是开发板的启动挂载仍然不行。
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是的NFS作为根文件系统，不能够进入shell，错误提示和一楼代码一样。uboot网络功能正常，能够正常ping通服务器地址，下面是我的uboot环境变量设置。
baudrate=115200
bootargs11=noinitrd root=/dev/nfs nfsroot=10.0.20.78:/home/cookie/nuc970bsp/rootfs ip=10.0.20.83:10.0.20.78:10.0.20.254:255.255.255.0::eth0:off console=ttyS0,115200n8 rdinit=/sbin/init
bootargs=noinitrd console=ttyS0,115200n8 root=/dev/nfs rw rdinit=/linuxrc nfsroot=10.0.20.78:/home/cookie/nuc970bsp/rootfs ip=10.0.20.195:10.0.20.78:10.0.20.254:255.255.255.0::eth0:off
bootcmd=nboot 0x7fc0 0 0x200000;bootm 0x7fc0
bootdelay=3
ethact=emac
ethaddr=00:00:00:11:66:88
ipaddr=10.0.20.196
netmask=255.255.255.0
rootpath=/home/cookie/nuc970bsp/rootfs
serverip=10.0.20.78
stderr=serial
stdin=serial
stdout=serial离线
启动过程串口输出是这样的
## Booting kernel from Legacy Image at 00007fc0 ...
Image Name:
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 4451904 Bytes = 4.2 MiB
Load Address: 00007fc0
Entry Point: 00008000
Verifying Checksum ... OK
SF: Detected W25Q128 with page size 4 KiB, total 16 MiB
SF: DeviceBooting Linux on physical CPU 0x0
Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Initializing cgroup subsys cpuacct
Linux version 3.10.101 (cookie@cookie-HP) (gcc version 4.8.4 (GCC) ) #13 PREEMPT Wed Oct 24 14:44:15 CST 2018
CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177
CPU: VIVT data cache, VIVT instruction cache
Machine: NUC970
Memory policy: ECC disabled, Data cache writeback
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 16256
Kernel command line: noinitrd console=ttyS0,115200n8 root=/dev/nfs rw rdinit=/linuxrc nfsroot=10.0.20.78:/home/cookie/nuc970bsp/rootfs ip=10.0.20.195:10.0.20.78:10.0.20.254:255.255.255.0::eth0:off
PID hash table entries: 256 (order: -2, 1024 bytes)
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 64MB = 64MB total
Memory: 60316k/60316k available, 5220k reserved, 0K highmem
Virtual kernel memory layout:
vector : 0xffff0000 - 0xffff1000 ( 4 kB)
fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
vmalloc : 0xc4800000 - 0xff000000 ( 936 MB)
lowmem : 0xc0000000 - 0xc4000000 ( 64 MB)
.text : 0xc0008000 - 0xc03e6f04 (3964 kB)
.init : 0xc03e7000 - 0xc0409680 ( 138 kB)
.data : 0xc040a000 - 0xc0446e40 ( 244 kB)
.bss : 0xc0446e40 - 0xc047da60 ( 220 kB)
SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Preemptible hierarchical RCU implementation.
NR_IRQS:625
sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 4294967286ms
Console: colour dummy device 80x30
console [ttyS0] enabled
Calibrating delay loop... 148.88 BogoMIPS (lpj=744448)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 512
Initializing cgroup subsys devices
Initializing cgroup subsys freezer
Initializing cgroup subsys perf_event
CPU: Testing write buffer coherency: ok
Setting up static identity map for 0xc0359d38 - 0xc0359d74
devtmpfs: initialized
pinctrl core: initialized pinctrl subsystem
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
bio: create slab <bio-0> at 0
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Switching to clocksource nuc970-timer1
cfg80211: Calling CRDA to update world regulatory domain
NET: Registered protocol family 2
TCP established hash table entries: 512 (order: 0, 4096 bytes)
TCP bind hash table entries: 512 (order: -1, 2048 bytes)
TCP: Hash tables configured (established 512 bind 512)
TCP: reno registered
UDP hash table entries: 256 (order: 0, 4096 bytes)
UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
NET: Registered protocol family 1
RPC: Registered named UNIX socket transport module.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
NetWinder Floating Point Emulator V0.97 (double precision)
NFS: Registering the id_resolver key type
Key type id_resolver registered
Key type id_legacy registered
nfs4filelayout_init: NFSv4 File Layout Driver Registering...
msgmni has been set to 117
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
io scheduler noop registered
io scheduler deadline registered
io scheduler cfq registered (default)
nuc970-uart.0: ttyS0 at I/O 0x0 (irq = 36) is a NUC970
brd: module loaded
nuc970 mtd nand driver version: 20160331
NAND device: Manufacturer ID: 0xad, Chip ID: 0xf1 (Hynix NAND 128MiB 3,3V 8-bit), 128MiB, page size: 2048, OOB size: 64
SYSTEM: USE BCH_T4 HWECC algorithm(SMRA size: 64, Parity number:32 bytes)
EXECUTE: USE BCH_T4 HWECC algorithm(SMRA size: 64, Parity number:32 bytes)
USE BCH_T4 HWECC algorithm(Parity number:32 bytes)
Bad block table found at page 65472, version 0x01
Bad block table found at page 65408, version 0x01
Creating 3 MTD partitions on "nand0":
0x000000000000-0x000000200000 : "u-boot"
0x000000200000-0x000001600000 : "Kernel"
0x000001600000-0x000008000000 : "user"
fmi-sm: registered successfully! mtdid=nand0
libphy: nuc970_rmii0: probed
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
nuc970-ehci nuc970-ehci: Nuvoton NUC970 EHCI Host Controller
nuc970-ehci nuc970-ehci: new USB bus registered, assigned bus number 1
nuc970-ehci nuc970-ehci: irq 23, io mem 0xb0005000
nuc970-ehci nuc970-ehci: USB 2.0 started, EHCI 0.95
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
nuc970-ohci nuc970-ohci: Nuvoton NUC970 OHCI Host Controller
nuc970-ohci nuc970-ohci: new USB bus registered, assigned bus number 2
nuc970-ohci nuc970-ohci: irq 24, io mem 0xb0007000
hub 2-0:1.0: USB hub found
hub 2-0:1.0: 2 ports detected
usbcore: registered new interface driver usb-storage
ipip: IPv4 over IPv4 tunneling driver
gre: GRE over IPv4 demultiplexor driver
ip_gre: GRE over IPv4 tunneling driver
TCP: cubic registered
NET: Registered protocol family 10
sit: IPv6 over IPv4 tunneling driver
NET: Registered protocol family 17
Key type dns_resolver registered
nuc970-emac0 nuc970-emac0: eth0 is OPENED
IP-Config: Complete:
device=eth0, hwaddr=08:00:27:00:01:92, ipaddr=10.0.20.195, mask=255.255.255.0, gw=10.0.20.254
host=10.0.20.195, domain=, nis-domain=(none)
bootserver=10.0.20.78, rootserver=10.0.20.78, rootpath=
VFS: Unable to mount root fs via NFS, trying floppy.
VFS: Cannot open root device "nfs" or unknown-block(2,0): error -6
Please append a correct "root=" boot option; here are the available partitions:
1f00 2048 mtdblock0 (driver?)
1f01 20480 mtdblock1 (driver?)
1f02 108544 mtdblock2 (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
CPU: 0 PID: 1 Comm: swapper Not tainted 3.10.101 #13
Backtrace:
[<c0011dc4>] (dump_backtrace+0x0/0x10c) from [<c0011f60>] (show_stack+0x18/0x1c)
r6:c0404eac r5:00008000 r4:c03b7e8c r3:00000000
[<c0011f48>] (show_stack+0x0/0x1c) from [<c0356c98>] (dump_stack+0x20/0x28)
[<c0356c78>] (dump_stack+0x0/0x28) from [<c0354894>] (panic+0xa4/0x1fc)
[<c03547f0>] (panic+0x0/0x1fc) from [<c03e81dc>] (mount_block_root+0x1c4/0x270)
r3:00000001 r2:00000000 r1:c3843ea0 r0:c03b7e8c
r7:c03b7ef4
[<c03e8018>] (mount_block_root+0x0/0x270) from [<c03e8470>] (mount_root+0xec/0x114)
[<c03e8384>] (mount_root+0x0/0x114) from [<c03e85f8>] (prepare_namespace+0x160/0x1c0)
r8:00000069 r7:c0404e8c r6:c0404eac r5:c0404eac r4:c0446ea0
[<c03e8498>] (prepare_namespace+0x0/0x1c0) from [<c03e7dd0>] (kernel_init_freeable+0x1f8/0x240)
r6:c03e74c8 r5:c0404e84 r4:00000007
[<c03e7bd8>] (kernel_init_freeable+0x0/0x240) from [<c03541f0>] (kernel_init+0x10/0x158)
[<c03541e0>] (kernel_init+0x0/0x158) from [<c000eb98>] (ret_from_fork+0x14/0x3c)
r5:c03541e0 r4:00000000离线
依然挂载不上去，现在感觉可能是我这边的服务器配置有问题，串口启动代码如下
## Booting kernel from Legacy Image at 00007fc0 ...
Image Name:
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 4451904 Bytes = 4.2 MiB
Load Address: 00007fc0
Entry Point: 00008000
Verifying Checksum ... OK
SF: Detected W25Q128 with page size 4 KiB, total 16 MiB
SF: DeviceBooting Linux on physical CPU 0x0
Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Initializing cgroup subsys cpuacct
Linux version 3.10.101 (cookie@cookie-HP) (gcc version 4.8.4 (GCC) ) #13 PREEMPT Wed Oct 24 14:44:15 CST 2018
CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177
CPU: VIVT data cache, VIVT instruction cache
Machine: NUC970
Memory policy: ECC disabled, Data cache writeback
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 16256
Kernel command line: noinitrd console=ttyS0,115200n8 root=/dev/nfs rw rdinit=/linuxrc nfsroot=10.0.20.78:/home/cookie/nuc970bsp/rootfs,nfsvers=3 ip=10.0.20.195:10.0.20.78:10.0.20.254:255.255.255.0::eth0:off
PID hash table entries: 256 (order: -2, 1024 bytes)
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 64MB = 64MB total
Memory: 60316k/60316k available, 5220k reserved, 0K highmem
Virtual kernel memory layout:
vector : 0xffff0000 - 0xffff1000 ( 4 kB)
fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
vmalloc : 0xc4800000 - 0xff000000 ( 936 MB)
lowmem : 0xc0000000 - 0xc4000000 ( 64 MB)
.text : 0xc0008000 - 0xc03e6f04 (3964 kB)
.init : 0xc03e7000 - 0xc0409680 ( 138 kB)
.data : 0xc040a000 - 0xc0446e40 ( 244 kB)
.bss : 0xc0446e40 - 0xc047da60 ( 220 kB)
SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Preemptible hierarchical RCU implementation.
NR_IRQS:625
sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 4294967286ms
Console: colour dummy device 80x30
console [ttyS0] enabled
Calibrating delay loop... 148.88 BogoMIPS (lpj=744448)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 512
Initializing cgroup subsys devices
Initializing cgroup subsys freezer
Initializing cgroup subsys perf_event
CPU: Testing write buffer coherency: ok
Setting up static identity map for 0xc0359d38 - 0xc0359d74
devtmpfs: initialized
pinctrl core: initialized pinctrl subsystem
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
bio: create slab <bio-0> at 0
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Switching to clocksource nuc970-timer1
cfg80211: Calling CRDA to update world regulatory domain
NET: Registered protocol family 2
TCP established hash table entries: 512 (order: 0, 4096 bytes)
TCP bind hash table entries: 512 (order: -1, 2048 bytes)
TCP: Hash tables configured (established 512 bind 512)
TCP: reno registered
UDP hash table entries: 256 (order: 0, 4096 bytes)
UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
NET: Registered protocol family 1
RPC: Registered named UNIX socket transport module.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
NetWinder Floating Point Emulator V0.97 (double precision)
NFS: Registering the id_resolver key type
Key type id_resolver registered
Key type id_legacy registered
nfs4filelayout_init: NFSv4 File Layout Driver Registering...
msgmni has been set to 117
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
io scheduler noop registered
io scheduler deadline registered
io scheduler cfq registered (default)
nuc970-uart.0: ttyS0 at I/O 0x0 (irq = 36) is a NUC970
brd: module loaded
nuc970 mtd nand driver version: 20160331
NAND device: Manufacturer ID: 0xad, Chip ID: 0xf1 (Hynix NAND 128MiB 3,3V 8-bit), 128MiB, page size: 2048, OOB size: 64
SYSTEM: USE BCH_T4 HWECC algorithm(SMRA size: 64, Parity number:32 bytes)
EXECUTE: USE BCH_T4 HWECC algorithm(SMRA size: 64, Parity number:32 bytes)
USE BCH_T4 HWECC algorithm(Parity number:32 bytes)
Bad block table found at page 65472, version 0x01
Bad block table found at page 65408, version 0x01
Creating 3 MTD partitions on "nand0":
0x000000000000-0x000000200000 : "u-boot"
0x000000200000-0x000001600000 : "Kernel"
0x000001600000-0x000008000000 : "user"
fmi-sm: registered successfully! mtdid=nand0
libphy: nuc970_rmii0: probed
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
nuc970-ehci nuc970-ehci: Nuvoton NUC970 EHCI Host Controller
nuc970-ehci nuc970-ehci: new USB bus registered, assigned bus number 1
nuc970-ehci nuc970-ehci: irq 23, io mem 0xb0005000
nuc970-ehci nuc970-ehci: USB 2.0 started, EHCI 0.95
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
nuc970-ohci nuc970-ohci: Nuvoton NUC970 OHCI Host Controller
nuc970-ohci nuc970-ohci: new USB bus registered, assigned bus number 2
nuc970-ohci nuc970-ohci: irq 24, io mem 0xb0007000
hub 2-0:1.0: USB hub found
hub 2-0:1.0: 2 ports detected
usbcore: registered new interface driver usb-storage
ipip: IPv4 over IPv4 tunneling driver
gre: GRE over IPv4 demultiplexor driver
ip_gre: GRE over IPv4 tunneling driver
TCP: cubic registered
NET: Registered protocol family 10
sit: IPv6 over IPv4 tunneling driver
NET: Registered protocol family 17
Key type dns_resolver registered
nuc970-emac0 nuc970-emac0: eth0 is OPENED
IP-Config: Complete:
device=eth0, hwaddr=08:00:27:00:01:92, ipaddr=10.0.20.195, mask=255.255.255.0, gw=10.0.20.254
host=10.0.20.195, domain=, nis-domain=(none)
bootserver=10.0.20.78, rootserver=10.0.20.78, rootpath=
VFS: Mounted root (nfs filesystem) on device 0:11.
devtmpfs: mounted
Freeing unused kernel memory: 136K (c03e7000 - c0409000)
nfs: server 10.0.20.78 not responding, still trying
nfs: server 10.0.20.78 not responding, still trying
nfs: server 10.0.20.78 OK
nfs: server 10.0.20.78 not responding, still trying
nfs: server 10.0.20.78 not responding, still trying离线
我的nfs配置文件/etc/exports 中配置如下,这里会不会和linux版本有关，我开发机是Ubuntu18.04的64位机。安装的是nfs-kernel-service软件包。
/home/cookie/nuc970bsp/rootfs *(rw,sync,no_subtree_check)离线
问题解决了，nfs协议默认使用UDP协议连接，掉包严重，需要指定NFS使用TCP协议来连接。这里需要更改的是在nfsroot加上tcp选项，添加之后的bootargs参数类似这样
bootargs=noinitrd console=ttyS0,115200n8 root=/dev/nfs rw rdinit=/linuxrc nfsroot=10.0.20.78:/home/cookie/nuc970bsp/rootfs,nfsvers=3,nolock,tcp评估板的网卡型号为ICplus PHYs，这个掉包严重的问题和这个网卡有关么 ？
最后非常感谢晕哥的耐心指导。不甚感激
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