前言

• 最近一段时间使用qemu来进行测试，为了方便调试，需要使用nfs和tftp等网络服务，这就必须为qemu添加网卡，通过网络搜索了对应的设置方法如下：
  • 在虚拟机添加第二个网卡，并设置为NET模式
  • 修改网络管理配置文件 /etc/netplan/01-network-manager-all.yaml
  • 修改/etc/qemu-ifup和/etc/qemu-ifdown脚本，qemu在启动前会调用该脚本初始化网卡，启动完成后再调用脚本关闭网卡
• 按照该方法在Ubuntu20上进行修改，工作起来并不稳定，有时候网络不通，另一个缺点是该方法还涉及虚拟机的设置，我的工作站上是物理机，运行Ubuntu22.04.LTS，因此该方法不能在我的工作站上运行，为此摸索出一个更简单的设置。

创建qemu虚拟网卡

• 创建TAP接口

 sudo ip tuntap add tap-qemu mode tap

• 为新创建的网卡分配IP地址

sudo ip addr add 192.168.1.1/24 dev tap-qemu

• 启动虚拟网卡工作

sudo ip link set tap-qemu up

• 使用ifconfig查看网卡状态

$ ifconfig
enp6s0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 00:e2:69:65:78:6b  txqueuelen 1000  (以太网)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (本地环回)
        RX packets 8515  bytes 983911 (983.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 8515  bytes 983911 (983.9 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

tap-qemu: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 192.168.1.1  netmask 255.255.255.0  broadcast 0.0.0.0
        inet6 fe80::94e7:88ff:fe99:7bc3  prefixlen 64  scopeid 0x20<link>
        ether 96:e7:88:99:7b:c3  txqueuelen 1000  (以太网)
        RX packets 44165  bytes 2332310 (2.3 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 46756  bytes 69222570 (69.2 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

• 运行qemu

qemu-system-arm -M vexpress-a9 -kernel u-boot -nographic -m 512M -nic tap,ifname=tap-qemu,script=no

• 运行结果

$ qemu-system-arm -M vexpress-a9 -kernel u-boot -nographic -m 512M -nic tap,ifname=tap-qemu,script=no
pulseaudio: set_sink_input_volume() failed
pulseaudio: Reason: Invalid argument
pulseaudio: set_sink_input_mute() failed
pulseaudio: Reason: Invalid argument


U-Boot 2022.07-rc3 (Jul 10 2023 - 01:10:49 +0800)

DRAM:  512 MiB
WARNING: Caches not enabled
Core:  19 devices, 10 uclasses, devicetree: embed
Flash: 64 MiB
MMC:   mmci@5000: 0
Loading Environment from Flash... *** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   eth0: ethernet@3,02000000
Hit any key to stop autoboot:  0 
smc911x: detected LAN9118 controller
smc911x: phy initialized
smc911x: MAC 52:54:00:12:34:56
Using ethernet@3,02000000 device
TFTP from server 192.168.1.1; our IP address is 192.168.1.2
Filename 'uImage'.
Load address: 0x60003000
Loading: #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #######################
         16.1 MiB/s
done
Bytes transferred = 5100056 (4dd218 hex)
smc911x: MAC 52:54:00:12:34:56
tftpboot - boot image via network using TFTP protocol

Usage:
tftpboot [loadAddress] [[hostIPaddr:]bootfilename]
smc911x: detected LAN9118 controller
smc911x: phy initialized
smc911x: MAC 52:54:00:12:34:56
Using ethernet@3,02000000 device
TFTP from server 192.168.1.1; our IP address is 192.168.1.2
Filename 'vexpress-v2p-ca9.dtb'.
Load address: 0x60800000
Loading: #
         6.8 MiB/s
done
Bytes transferred = 14171 (375b hex)
smc911x: MAC 52:54:00:12:34:56
## Booting kernel from Legacy Image at 60003000 ...
   Image Name:   Linux-5.10.99
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    5099992 Bytes = 4.9 MiB
   Load Address: 60008000
   Entry Point:  60008000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 60800000
   Booting using the fdt blob at 0x60800000
   Loading Kernel Image
   Loading Device Tree to 7fb1d000, end 7fb2375a ... OK

Starting kernel ...

Booting Linux on physical CPU 0x0
Linux version 5.10.99 (lhq@maxsun-ubuntu) (arm-linux-gnueabi-gcc (Ubuntu 11.3.0-1ubuntu1~22.04.1) 11.3.0, GNU ld (GNU Binutils for Ubuntu) 2.38) #2 SMP Mon Jul 10 00:44:41 CST 2023
CPU: ARMv7 Processor [410fc090] revision 0 (ARMv7), cr=10c5387d
CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing instruction cache
OF: fdt: Machine model: V2P-CA9
OF: fdt: Ignoring memory block 0x80000000 - 0x80000004
Memory policy: Data cache writeback
Reserved memory: created DMA memory pool at 0x4c000000, size 8 MiB
OF: reserved mem: initialized node vram@4c000000, compatible id shared-dma-pool
cma: Reserved 16 MiB at 0x7e800000
Zone ranges:
  Normal   [mem 0x0000000060000000-0x000000007fffffff]
Movable zone start for each node
Early memory node ranges
  node   0: [mem 0x0000000060000000-0x000000007fffffff]
Initmem setup node 0 [mem 0x0000000060000000-0x000000007fffffff]
CPU: All CPU(s) started in SVC mode.
percpu: Embedded 19 pages/cpu s46156 r8192 d23476 u77824
Built 1 zonelists, mobility grouping on.  Total pages: 130048
Kernel command line: root=/dev/nfs rw nfsroot=192.168.1.1:/home/lhq/Kernel/nfs,proto=tcp,nfsvers=3,nolock init=/linuxrc ip=192.168.1.2 console=ttyAMA0
printk: log_buf_len individual max cpu contribution: 4096 bytes
printk: log_buf_len total cpu_extra contributions: 12288 bytes
printk: log_buf_len min size: 16384 bytes
printk: log_buf_len: 32768 bytes
printk: early log buf free: 14644(89%)
Dentry cache hash table entries: 65536 (order: 6, 262144 bytes, linear)
Inode-cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
mem auto-init: stack:off, heap alloc:off, heap free:off
Memory: 490652K/524288K available (8192K kernel code, 760K rwdata, 1816K rodata, 1024K init, 185K bss, 17252K reserved, 16384K cma-reserved)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
rcu: Hierarchical RCU implementation.
rcu:    RCU event tracing is enabled.
rcu:    RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=4
NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
GIC CPU mask not found - kernel will fail to boot.
GIC CPU mask not found - kernel will fail to boot.
L2C: platform modifies aux control register: 0x02020000 -> 0x02420000
L2C: DT/platform modifies aux control register: 0x02020000 -> 0x02420000
L2C-310 enabling early BRESP for Cortex-A9
L2C-310 full line of zeros enabled for Cortex-A9
L2C-310 dynamic clock gating disabled, standby mode disabled
L2C-310 cache controller enabled, 8 ways, 128 kB
L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x46420001
random: get_random_bytes called from start_kernel+0x380/0x53c with crng_init=0
sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
clocksource: arm,sp804: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275 ns
Failed to initialize '/bus@40000000/motherboard/iofpga@7,00000000/timer@12000': -22
smp_twd: clock not found -2
Console: colour dummy device 80x30
Calibrating local timer... 95.34MHz.
Calibrating delay loop... 2393.70 BogoMIPS (lpj=11968512)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
CPU: Testing write buffer coherency: ok
CPU0: Spectre v2: using BPIALL workaround
CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Setting up static identity map for 0x60100000 - 0x60100060
rcu: Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
smp: Brought up 1 node, 1 CPU
SMP: Total of 1 processors activated (2393.70 BogoMIPS).
CPU: All CPU(s) started in SVC mode.
devtmpfs: initialized
VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 0
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
cpuidle: using governor ladder
hw-breakpoint: debug architecture 0x4 unsupported.
Serial: AMBA PL011 UART driver
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Advanced Linux Sound Architecture Driver Initialized.
clocksource: Switched to clocksource arm,sp804
NET: Registered protocol family 2
IP idents hash table entries: 8192 (order: 4, 65536 bytes, linear)
tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes, linear)
TCP established hash table entries: 4096 (order: 2, 16384 bytes, linear)
TCP bind hash table entries: 4096 (order: 3, 32768 bytes, linear)
TCP: Hash tables configured (established 4096 bind 4096)
UDP hash table entries: 256 (order: 1, 8192 bytes, linear)
UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)
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.
hw perfevents: enabled with armv7_cortex_a9 PMU driver, 5 counters available
workingset: timestamp_bits=30 max_order=17 bucket_order=0
squashfs: version 4.0 (2009/01/31) Phillip Lougher
NFS: Registering the id_resolver key type
Key type id_resolver registered
Key type id_legacy registered
nfs4filelayout_init: NFSv4 File Layout Driver Registering...
nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering...
jffs2: version 2.2. (NAND) © 2001-2006 Red Hat, Inc.
9p: Installing v9fs 9p2000 file system support
io scheduler mq-deadline registered
io scheduler kyber registered
sii902x 0-0039: supply iovcc not found, using dummy regulator
sii902x 0-0039: supply cvcc12 not found, using dummy regulator
i2c i2c-0: Added multiplexed i2c bus 2
sii902x 0-0060: supply iovcc not found, using dummy regulator
sii902x 0-0060: supply cvcc12 not found, using dummy regulator
physmap-flash 40000000.flash: physmap platform flash device: [mem 0x40000000-0x43ffffff]
40000000.flash: Found 2 x16 devices at 0x0 in 32-bit bank. Manufacturer ID 0x000000 Chip ID 0x000000
Intel/Sharp Extended Query Table at 0x0031
Using buffer write method
physmap-flash 40000000.flash: physmap platform flash device: [mem 0x44000000-0x47ffffff]
40000000.flash: Found 2 x16 devices at 0x0 in 32-bit bank. Manufacturer ID 0x000000 Chip ID 0x000000
Intel/Sharp Extended Query Table at 0x0031
Using buffer write method
Concatenating MTD devices:
(0): "40000000.flash"
(1): "40000000.flash"
into device "40000000.flash"
physmap-flash 48000000.psram: physmap platform flash device: [mem 0x48000000-0x49ffffff]
smsc911x 4e000000.ethernet eth0: MAC Address: 52:54:00:12:34:56
isp1760 4f000000.usb: bus width: 32, oc: digital
isp1760 4f000000.usb: NXP ISP1760 USB Host Controller
isp1760 4f000000.usb: new USB bus registered, assigned bus number 1
isp1760 4f000000.usb: Scratch test failed.
isp1760 4f000000.usb: can't setup: -19
isp1760 4f000000.usb: USB bus 1 deregistered
usbcore: registered new interface driver usb-storage
ledtrig-cpu: registered to indicate activity on CPUs
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
NET: Registered protocol family 17
9pnet: Installing 9P2000 support
Key type dns_resolver registered
oprofile: using arm/armv7-ca9
Registering SWP/SWPB emulation handler
aaci-pl041 10004000.aaci: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 28
aaci-pl041 10004000.aaci: FIFO 512 entries
mmci-pl18x 10005000.mmci: Got CD GPIO
mmci-pl18x 10005000.mmci: Got WP GPIO
mmci-pl18x 10005000.mmci: mmc0: PL181 manf 41 rev0 at 0x10005000 irq 29,30 (pio)
10009000.uart: ttyAMA0 at MMIO 0x10009000 (irq = 33, base_baud = 0) is a PL011 rev1
printk: console [ttyAMA0] enabled
1000a000.uart: ttyAMA1 at MMIO 0x1000a000 (irq = 34, base_baud = 0) is a PL011 rev1
1000b000.uart: ttyAMA2 at MMIO 0x1000b000 (irq = 35, base_baud = 0) is a PL011 rev1
1000c000.uart: ttyAMA3 at MMIO 0x1000c000 (irq = 36, base_baud = 0) is a PL011 rev1
rtc-pl031 10017000.rtc: registered as rtc0
rtc-pl031 10017000.rtc: setting system clock to 2023-07-10T02:10:56 UTC (1688955056)
drm-clcd-pl111 1001f000.clcd: assigned reserved memory node vram@4c000000
drm-clcd-pl111 1001f000.clcd: using device-specific reserved memory
drm-clcd-pl111 1001f000.clcd: core tile graphics present
drm-clcd-pl111 1001f000.clcd: this device will be deactivated
drm-clcd-pl111 1001f000.clcd: Versatile Express init failed - -19
drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111
drm-clcd-pl111 10020000.clcd: found bridge on endpoint 0
drm-clcd-pl111 10020000.clcd: Using non-panel bridge
[drm] Initialized pl111 1.0.0 20170317 for 10020000.clcd on minor 0
input: AT Raw Set 2 keyboard as /devices/platform/bus@40000000/bus@40000000:motherboard/bus@40000000:motherboard:iofpga@7,00000000/10006000.kmi/serio0/input/input0
Console: switching to colour frame buffer device 128x48
drm-clcd-pl111 10020000.clcd: [drm] fb0: pl111drmfb frame buffer device
input: ImExPS/2 Generic Explorer Mouse as /devices/platform/bus@40000000/bus@40000000:motherboard/bus@40000000:motherboard:iofpga@7,00000000/10007000.kmi/serio1/input/input2
Generic PHY 4e000000.ethernet-ffffffff:01: attached PHY driver [Generic PHY] (mii_bus:phy_addr=4e000000.ethernet-ffffffff:01, irq=POLL)
smsc911x 4e000000.ethernet eth0: SMSC911x/921x identified at 0xa08b0000, IRQ: 26
IP-Config: Guessing netmask 255.255.255.0
IP-Config: Complete:
     device=eth0, hwaddr=52:54:00:12:34:56, ipaddr=192.168.1.2, mask=255.255.255.0, gw=255.255.255.255
     host=192.168.1.2, domain=, nis-domain=(none)
     bootserver=255.255.255.255, rootserver=192.168.1.1, rootpath=
ALSA device list:
  #0: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 28
VFS: Mounted root (nfs filesystem) on device 0:14.
Freeing unused kernel memory: 1024K
Run /linuxrc as init process
random: fast init done
-----------------------------------
*****welcome to vexpress board*****
-----------------------------------

Please press Enter to activate this console. 
[root@vexpress ]# ifconfig
eth0      Link encap:Ethernet  HWaddr 52:54:00:12:34:56  
          inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2461 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1301 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:3322660 (3.1 MiB)  TX bytes:204394 (199.6 KiB)
          Interrupt:26 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

[root@vexpress ]# QEMU: Terminated