任务三：Linux 6.1 + 网卡驱动 在 Qemu for x86/AArch64 中运行
背景知识
Linux 镜像如何添加驱动,安装 virtio 驱动（Linux）
PCI：接口
-netdev 设置接口
NIC：网卡
-device 设置网卡
参考配置
Boot options
Here is a simple setup with one e1000e NIC :
$ qemu-system-ppc64 -m 2G -machine powernv9 -smp 2,cores=2,threads=1 \ -accel tcg,thread=single \ -device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02,bus=pcie.0,addr=0x0 \ -netdev user,id=net0,hostfwd=::20022-:22,hostname=pnv \ -kernel ./zImage.epapr \ -initrd ./rootfs.cpio.xz \ -nographic
zCore 里面模拟了 e1000 网卡，qemu_opts 需要增加 2 行以指定 e1000
qemu_opts += \
-netdev user,id=net1,hostfwd=tcp::8000-:80,hostfwd=tcp::2222-:2222,hostfwd=udp::6969-:6969 \
-device e1000e,netdev=net1
参考：Documentation/Networking - QEMU
-
编译内核
make clean make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig make -j4 ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- Image modules dtbs -
运行
qemu-system-aarch64 -M virt -cpu cortex-a72 -smp 8 -m 128M -kernel (your Image path) -initrd (your initramfs.cpio.gz path) -nographic -netdev user,id=net0 -device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02例如：
qemu-system-aarch64 -M virt -cpu cortex-a72 -smp 8 -m 128M -kernel (your Image path) -initrd (your initramfs.cpio.gz path) -nographic -netdev user,id=net0 -device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02-netdev user是设置网络接口为 user，-device是指定网卡，此处是使用 e1000e下面是运行结果：
qemu-system-aarch64 -M virt -cpu cortex-a72 -smp 8 -m 128M -kernel /home/jun/maodou/linux/arch/arm64/boot/Image -initrd /home/jun/maodou/busybox-1.35.0/initramfs.cpio.gz -nographic -netdev user,id=net0 -device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02 [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd083] [ 0.000000] Linux version 6.1.25-gfc30a915ea61-dirty (jun@DESKTOP-L2BA3J3) (aarch64-linux-gnu-gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0, GNU ld (GNU Binutils for Ubuntu) 2.38) #6 SMP PREEMPT Sun Apr 30 13:48:59 CST 2023 [ 0.000000] Machine model: linux,dummy-virt [ 0.000000] efi: UEFI not found. [ 0.000000] NUMA: No NUMA configuration found [ 0.000000] NUMA: Faking a node at [mem 0x0000000040000000-0x0000000047ffffff] [ 0.000000] NUMA: NODE_DATA [mem 0x47fafa00-0x47fb1fff] [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x0000000040000000-0x0000000047ffffff] [ 0.000000] DMA32 empty [ 0.000000] Normal empty [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000040000000-0x0000000047ffffff] [ 0.000000] Initmem setup node 0 [mem 0x0000000040000000-0x0000000047ffffff] [ 0.000000] cma: Reserved 32 MiB at 0x0000000045c00000 [ 0.000000] psci: probing for conduit method from DT. [ 0.000000] psci: PSCIv0.2 detected in firmware. [ 0.000000] psci: Using standard PSCI v0.2 function IDs [ 0.000000] psci: Trusted OS migration not required [ 0.000000] percpu: Embedded 20 pages/cpu s44840 r8192 d28888 u81920 [ 0.000000] Detected PIPT I-cache on CPU0 [ 0.000000] CPU features: detected: Spectre-v2 [ 0.000000] CPU features: detected: Spectre-v3a [ 0.000000] CPU features: detected: Spectre-v4 [ 0.000000] CPU features: detected: Spectre-BHB [ 0.000000] CPU features: kernel page table isolation forced ON by KASLR [ 0.000000] CPU features: detected: Kernel page table isolation (KPTI) [ 0.000000] CPU features: detected: ARM erratum 1742098 [ 0.000000] CPU features: detected: ARM errata 1165522, 1319367, or 1530923 [ 0.000000] alternatives: applying boot alternatives [ 0.000000] Fallback order for Node 0: 0 [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 32256 [ 0.000000] Policy zone: DMA [ 0.000000] Kernel command line: [ 0.000000] Dentry cache hash table entries: 16384 (order: 5, 131072 bytes, linear) [ 0.000000] Inode-cache hash table entries: 8192 (order: 4, 65536 bytes, linear) [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off [ 0.000000] Memory: 56008K/131072K available (16064K kernel code, 3706K rwdata, 8836K rodata, 7552K init, 609K bss, 42296K reserved, 32768K cma-reserved) [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=8, Nodes=1 [ 0.000000] rcu: Preemptible hierarchical RCU implementation. [ 0.000000] rcu: RCU event tracing is enabled. [ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=256 to nr_cpu_ids=8. [ 0.000000] Trampoline variant of Tasks RCU enabled. [ 0.000000] Tracing variant of Tasks RCU enabled. [ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies. [ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=8 [ 0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0 [ 0.000000] Root IRQ handler: gic_handle_irq [ 0.000000] GICv2m: range[mem 0x08020000-0x08020fff], SPI[80:143] [ 0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention. [ 0.000000] arch_timer: cp15 timer(s) running at 62.50MHz (virt). [ 0.000000] clocksource: arch_sys_counter: mask: 0x1ffffffffffffff max_cycles: 0x1cd42e208c, max_idle_ns: 881590405314 ns [ 0.000076] sched_clock: 57 bits at 63MHz, resolution 16ns, wraps every 4398046511096ns [ 0.007920] Console: colour dummy device 80x25 [ 0.010044] printk: console [tty0] enabled [ 0.012330] Calibrating delay loop (skipped), value calculated using timer frequency.. 125.00 BogoMIPS (lpj=250000) [ 0.012500] pid_max: default: 32768 minimum: 301 [ 0.013262] LSM: Security Framework initializing [ 0.016003] Mount-cache hash table entries: 512 (order: 0, 4096 bytes, linear) [ 0.016065] Mountpoint-cache hash table entries: 512 (order: 0, 4096 bytes, linear) [ 0.047451] cgroup: Disabling memory control group subsystem [ 0.063952] cacheinfo: Unable to detect cache hierarchy for CPU 0 [ 0.070942] cblist_init_generic: Setting adjustable number of callback queues. [ 0.071145] cblist_init_generic: Setting shift to 3 and lim to 1. [ 0.071441] cblist_init_generic: Setting shift to 3 and lim to 1. [ 0.072850] rcu: Hierarchical SRCU implementation. [ 0.072904] rcu: Max phase no-delay instances is 1000. [ 0.078647] EFI services will not be available. [ 0.080163] smp: Bringing up secondary CPUs ... [ 0.083812] Detected PIPT I-cache on CPU1 [ 0.084409] cacheinfo: Unable to detect cache hierarchy for CPU 1 [ 0.084815] CPU1: Booted secondary processor 0x0000000001 [0x410fd083] [ 0.089347] Detected PIPT I-cache on CPU2 [ 0.089523] cacheinfo: Unable to detect cache hierarchy for CPU 2 [ 0.089738] CPU2: Booted secondary processor 0x0000000002 [0x410fd083] [ 0.091006] Detected PIPT I-cache on CPU3 [ 0.091154] cacheinfo: Unable to detect cache hierarchy for CPU 3 [ 0.091279] CPU3: Booted secondary processor 0x0000000003 [0x410fd083] [ 0.092569] Detected PIPT I-cache on CPU4 [ 0.092704] cacheinfo: Unable to detect cache hierarchy for CPU 4 [ 0.092838] CPU4: Booted secondary processor 0x0000000004 [0x410fd083] [ 0.094313] Detected PIPT I-cache on CPU5 [ 0.094455] cacheinfo: Unable to detect cache hierarchy for CPU 5 [ 0.094612] CPU5: Booted secondary processor 0x0000000005 [0x410fd083] [ 0.096838] Detected PIPT I-cache on CPU6 [ 0.097059] cacheinfo: Unable to detect cache hierarchy for CPU 6 [ 0.097407] CPU6: Booted secondary processor 0x0000000006 [0x410fd083] [ 0.098799] Detected PIPT I-cache on CPU7 [ 0.098941] cacheinfo: Unable to detect cache hierarchy for CPU 7 [ 0.099114] CPU7: Booted secondary processor 0x0000000007 [0x410fd083] [ 0.099976] smp: Brought up 1 node, 8 CPUs [ 0.100270] SMP: Total of 8 processors activated. [ 0.100373] CPU features: detected: 32-bit EL0 Support [ 0.100415] CPU features: detected: 32-bit EL1 Support [ 0.100493] CPU features: detected: CRC32 instructions [ 0.104523] CPU: All CPU(s) started at EL1 [ 0.104766] alternatives: applying system-wide alternatives [ 0.134654] devtmpfs: initialized [ 0.151198] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns [ 0.151670] futex hash table entries: 2048 (order: 5, 131072 bytes, linear) [ 0.156256] pinctrl core: initialized pinctrl subsystem [ 0.167152] DMI not present or invalid. [ 0.178729] NET: Registered PF_NETLINK/PF_ROUTE protocol family [ 0.191012] DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations [ 0.192709] DMA: preallocated 128 KiB GFP_KERNEL|GFP_DMA pool for atomic allocations [ 0.193016] DMA: preallocated 128 KiB GFP_KERNEL|GFP_DMA32 pool for atomic allocations [ 0.193311] audit: initializing netlink subsys (disabled) [ 0.195980] audit: type=2000 audit(0.176:1): state=initialized audit_enabled=0 res=1 [ 0.201001] thermal_sys: Registered thermal governor 'step_wise' [ 0.201119] thermal_sys: Registered thermal governor 'power_allocator' [ 0.201591] cpuidle: using governor menu [ 0.202702] hw-breakpoint: found 6 breakpoint and 4 watchpoint registers. [ 0.204553] ASID allocator initialised with 32768 entries [ 0.210462] Serial: AMBA PL011 UART driver [ 0.250626] 9000000.pl011: ttyAMA0 at MMIO 0x9000000 (irq = 13, base_baud = 0) is a PL011 rev1 [ 0.412612] printk: console [ttyAMA0] enabled [ 0.432545] KASLR enabled [ 0.465245] HugeTLB: registered 1.00 GiB page size, pre-allocated 0 pages [ 0.468073] HugeTLB: 0 KiB vmemmap can be freed for a 1.00 GiB page [ 0.469774] HugeTLB: registered 32.0 MiB page size, pre-allocated 0 pages [ 0.473402] HugeTLB: 0 KiB vmemmap can be freed for a 32.0 MiB page [ 0.474257] HugeTLB: registered 2.00 MiB page size, pre-allocated 0 pages [ 0.478495] HugeTLB: 0 KiB vmemmap can be freed for a 2.00 MiB page [ 0.479951] HugeTLB: registered 64.0 KiB page size, pre-allocated 0 pages [ 0.481171] HugeTLB: 0 KiB vmemmap can be freed for a 64.0 KiB page [ 0.497351] ACPI: Interpreter disabled. [ 0.506097] iommu: Default domain type: Translated [ 0.507213] iommu: DMA domain TLB invalidation policy: strict mode [ 0.512840] SCSI subsystem initialized [ 0.517128] usbcore: registered new interface driver usbfs [ 0.517968] usbcore: registered new interface driver hub [ 0.518780] usbcore: registered new device driver usb [ 0.526644] pps_core: LinuxPPS API ver. 1 registered [ 0.527189] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it> [ 0.529573] PTP clock support registered [ 0.530874] EDAC MC: Ver: 3.0.0 [ 0.540321] FPGA manager framework [ 0.543878] Advanced Linux Sound Architecture Driver Initialized. [ 0.561118] vgaarb: loaded [ 0.574033] clocksource: Switched to clocksource arch_sys_counter [ 0.577531] VFS: Disk quotas dquot_6.6.0 [ 0.579154] VFS: Dquot-cache hash table entries: 512 (order 0, 4096 bytes) [ 0.589008] pnp: PnP ACPI: disabled [ 0.633693] NET: Registered PF_INET protocol family [ 0.636445] IP idents hash table entries: 2048 (order: 2, 16384 bytes, linear) [ 0.648946] tcp_listen_portaddr_hash hash table entries: 256 (order: 0, 4096 bytes, linear) [ 0.649690] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear) [ 0.650529] TCP established hash table entries: 1024 (order: 1, 8192 bytes, linear) [ 0.651585] TCP bind hash table entries: 1024 (order: 3, 32768 bytes, linear) [ 0.652841] TCP: Hash tables configured (established 1024 bind 1024) [ 0.655092] UDP hash table entries: 256 (order: 1, 8192 bytes, linear) [ 0.655707] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear) [ 0.660727] NET: Registered PF_UNIX/PF_LOCAL protocol family [ 0.666423] RPC: Registered named UNIX socket transport module. [ 0.667081] RPC: Registered udp transport module. [ 0.668086] RPC: Registered tcp transport module. [ 0.668547] RPC: Registered tcp NFSv4.1 backchannel transport module. [ 0.669484] PCI: CLS 0 bytes, default 64 [ 0.678630] Unpacking initramfs... [ 0.682946] hw perfevents: enabled with armv8_pmuv3 PMU driver, 5 counters available [ 0.689163] kvm [1]: HYP mode not available [ 0.698184] Initialise system trusted keyrings [ 0.705175] workingset: timestamp_bits=42 max_order=15 bucket_order=0 [ 0.730389] squashfs: version 4.0 (2009/01/31) Phillip Lougher [ 0.736416] NFS: Registering the id_resolver key type [ 0.740411] Key type id_resolver registered [ 0.743369] Key type id_legacy registered [ 0.745312] nfs4filelayout_init: NFSv4 File Layout Driver Registering... [ 0.749096] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering... [ 0.753622] 9p: Installing v9fs 9p2000 file system support [ 0.800839] Key type asymmetric registered [ 0.801297] Asymmetric key parser 'x509' registered [ 0.802532] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 245) [ 0.803498] io scheduler mq-deadline registered [ 0.804339] io scheduler kyber registered [ 0.850819] Freeing initrd memory: 1140K [ 0.853844] pl061_gpio 9030000.pl061: PL061 GPIO chip registered [ 0.862556] pci-host-generic 4010000000.pcie: host bridge /pcie@10000000 ranges: [ 0.864113] pci-host-generic 4010000000.pcie: IO 0x003eff0000..0x003effffff -> 0x0000000000 [ 0.865492] pci-host-generic 4010000000.pcie: MEM 0x0010000000..0x003efeffff -> 0x0010000000 [ 0.865949] pci-host-generic 4010000000.pcie: MEM 0x8000000000..0xffffffffff -> 0x8000000000 [ 0.867194] pci-host-generic 4010000000.pcie: Memory resource size exceeds max for 32 bits [ 0.869698] pci-host-generic 4010000000.pcie: ECAM at [mem 0x4010000000-0x401fffffff] for [bus 00-ff] [ 0.872749] pci-host-generic 4010000000.pcie: PCI host bridge to bus 0000:00 [ 0.873662] pci_bus 0000:00: root bus resource [bus 00-ff] [ 0.874127] pci_bus 0000:00: root bus resource [io 0x0000-0xffff] [ 0.874910] pci_bus 0000:00: root bus resource [mem 0x10000000-0x3efeffff] [ 0.875453] pci_bus 0000:00: root bus resource [mem 0x8000000000-0xffffffffff] [ 0.878873] pci 0000:00:00.0: [1b36:0008] type 00 class 0x060000 [ 0.885660] pci 0000:00:01.0: [8086:10d3] type 00 class 0x020000 [ 0.886295] pci 0000:00:01.0: reg 0x10: [mem 0x00000000-0x0001ffff] [ 0.886750] pci 0000:00:01.0: reg 0x14: [mem 0x00000000-0x0001ffff] [ 0.887329] pci 0000:00:01.0: reg 0x18: [io 0x0000-0x001f] [ 0.888488] pci 0000:00:01.0: reg 0x1c: [mem 0x00000000-0x00003fff] [ 0.888783] pci 0000:00:01.0: reg 0x30: [mem 0x00000000-0x0007ffff pref] [ 0.894141] pci 0000:00:01.0: BAR 6: assigned [mem 0x10000000-0x1007ffff pref] [ 0.894784] pci 0000:00:01.0: BAR 0: assigned [mem 0x10080000-0x1009ffff] [ 0.895135] pci 0000:00:01.0: BAR 1: assigned [mem 0x100a0000-0x100bffff] [ 0.895491] pci 0000:00:01.0: BAR 3: assigned [mem 0x100c0000-0x100c3fff] [ 0.895865] pci 0000:00:01.0: BAR 2: assigned [io 0x1000-0x101f] [ 0.903785] EINJ: ACPI disabled. [ 0.973656] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled [ 0.982418] SuperH (H)SCI(F) driver initialized [ 0.983837] msm_serial: driver initialized [ 0.988656] cacheinfo: Unable to detect cache hierarchy for CPU 0 [ 1.015481] loop: module loaded [ 1.018467] megasas: 07.719.03.00-rc1 [ 1.026907] physmap-flash 0.flash: physmap platform flash device: [mem 0x00000000-0x03ffffff] [ 1.029881] 0.flash: Found 2 x16 devices at 0x0 in 32-bit bank. Manufacturer ID 0x000000 Chip ID 0x000000 [ 1.032254] Intel/Sharp Extended Query Table at 0x0031 [ 1.033856] Using buffer write method [ 1.034612] physmap-flash 0.flash: physmap platform flash device: [mem 0x04000000-0x07ffffff] [ 1.035784] 0.flash: Found 2 x16 devices at 0x0 in 32-bit bank. Manufacturer ID 0x000000 Chip ID 0x000000 [ 1.036668] Intel/Sharp Extended Query Table at 0x0031 [ 1.037892] Using buffer write method [ 1.042241] Concatenating MTD devices: [ 1.043181] (0): "0.flash" [ 1.043340] (1): "0.flash" [ 1.043475] into device "0.flash" [ 1.135325] tun: Universal TUN/TAP device driver, 1.6 [ 1.139309] thunder_xcv, ver 1.0 [ 1.140468] thunder_bgx, ver 1.0 [ 1.141381] nicpf, ver 1.0 [ 1.145694] hns3: Hisilicon Ethernet Network Driver for Hip08 Family - version [ 1.146002] hns3: Copyright (c) 2017 Huawei Corporation. [ 1.146554] hclge is initializing [ 1.146788] e1000: Intel(R) PRO/1000 Network Driver [ 1.146926] e1000: Copyright (c) 1999-2006 Intel Corporation. [ 1.147300] e1000e: Intel(R) PRO/1000 Network Driver [ 1.147497] e1000e: Copyright(c) 1999 - 2015 Intel Corporation. [ 1.149866] e1000e 0000:00:01.0: enabling device (0000 -> 0002) [ 1.153859] e1000e 0000:00:01.0: Interrupt Throttling Rate (ints/sec) set to dynamic conservative mode [ 1.210632] e1000e 0000:00:01.0 0000:00:01.0 (uninitialized): registered PHC clock [ 1.267834] e1000e 0000:00:01.0 eth0: (PCI Express:2.5GT/s:Width x1) c0:ff:ee:00:00:02 [ 1.269040] e1000e 0000:00:01.0 eth0: Intel(R) PRO/1000 Network Connection [ 1.269793] e1000e 0000:00:01.0 eth0: MAC: 3, PHY: 8, PBA No: 000000-000 [ 1.270558] igb: Intel(R) Gigabit Ethernet Network Driver [ 1.270842] igb: Copyright (c) 2007-2014 Intel Corporation. [ 1.271492] igbvf: Intel(R) Gigabit Virtual Function Network Driver [ 1.272275] igbvf: Copyright (c) 2009 - 2012 Intel Corporation. [ 1.273745] sky2: driver version 1.30 [ 1.277125] VFIO - User Level meta-driver version: 0.3 [ 1.287749] usbcore: registered new interface driver usb-storage [ 1.301808] rtc-pl031 9010000.pl031: registered as rtc0 [ 1.302825] rtc-pl031 9010000.pl031: setting system clock to 2023-04-30T06:10:30 UTC (1682835030) [ 1.305806] i2c_dev: i2c /dev entries driver [ 1.323678] sdhci: Secure Digital Host Controller Interface driver [ 1.324345] sdhci: Copyright(c) Pierre Ossman [ 1.327161] Synopsys Designware Multimedia Card Interface Driver [ 1.329910] sdhci-pltfm: SDHCI platform and OF driver helper [ 1.338273] ledtrig-cpu: registered to indicate activity on CPUs [ 1.346070] usbcore: registered new interface driver usbhid [ 1.346365] usbhid: USB HID core driver [ 1.366689] NET: Registered PF_PACKET protocol family [ 1.368545] 9pnet: Installing 9P2000 support [ 1.369227] Key type dns_resolver registered [ 1.371120] registered taskstats version 1 [ 1.371594] Loading compiled-in X.509 certificates [ 1.452939] input: gpio-keys as /devices/platform/gpio-keys/input/input0 [ 1.466718] ALSA device list: [ 1.466984] No soundcards found. [ 1.474464] uart-pl011 9000000.pl011: no DMA platform data [ 1.532887] Freeing unused kernel memory: 7552K [ 1.536640] Run /init as init process Hello 64-bit ARM Linux This boot took 10732.04 seconds / # ls bin init proc sbin tmp dev linuxrc root sys usr / # ifconfig / # ifconfig -a eth0 Link encap:Ethernet HWaddr C0:FF:EE:00:00:02 BROADCAST MULTICAST MTU:1500 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) Interrupt:16 Memory:10080000-100a0000 lo Link encap:Local Loopback LOOPBACK 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) / # ifconfig lo up / # ping 127.0.0.1 PING 127.0.0.1 (127.0.0.1): 56 data bytes 64 bytes from 127.0.0.1: seq=0 ttl=64 time=12.804 ms 64 bytes from 127.0.0.1: seq=1 ttl=64 time=0.570 ms 64 bytes from 127.0.0.1: seq=2 ttl=64 time=0.492 ms
注意
ifconfig命令只能显示已经激活的网卡，要想看到本地已有的网卡需要使用ifconfig -a。另外，不管是模拟 e1000 还是 virtio_net，如果成功都将以 eth0 的形式出现。可以看到 eth0 网卡的 mac 地址，与运行 qemu 时所用的参数：
-device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02中设置的 mac 地址是一致的。 从运行结果可以看出，当网络接口为 user 的时候，在使用命令
ifconfig lo up，激活 lo (回环接口)之后，能够成功ping 127.0.0.1(本地 ip)。
但是，激活 eth0 网卡之后，并不能 ping 任何 ip ，包括本地 ip ：
依据 qemu 官方文档https://wiki.qemu.org/Documentation/Networking，若想要 ping 得其他 ip，需要将网络接口设置为 tap 。 将
-netdev user改为-netdev tap，执行：sudo qemu-system-aarch64 -M virt -cpu cortex-a72 -smp 8 -m 128M -kernel /home/jun/maodou/linux/arch/arm64/boot/Image -initrd /home/jun/maodou/busybox-1.35.0/initramfs.cpio.gz -nographic -netdev tap,id=net0 -device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02
可以成功运行，但是在 eth0 被激活的状态下，
sudo qemu-system-aarch64 -M virt -cpu cortex-a72 -smp 8 -m 128M -kernel /home/jun/maodou/linux/arch/arm64/boot/Image -initrd /home/jun/maodou/busybox-1.35.0/initramfs.cpio.gz -nographic -netdev tap,id=net0,ifname=tap0 -device e1000e,netdev=net0,mac=C0:FF:EE:00:00:02无法 ping 外网。
如果使用
ifconfig eth0 arbitrary_ip命令设置 eth0 的 ip，此处是 123.123.12.13：
可以看到如果只激活 eth0，无法 ping eth0 网卡的 ip。
但是在激活 lo 网卡之后，是可以 ping eth0 网卡的 ip 的。