如何在 QEMU 中不联网的情况下与主机共享目录？

Question

我的问题是我的设备树中的网络设备不是很稳定，所以我认为在 qemu 和主机系统之间共享文件夹的最佳方法是在双方没有缓存的情况下安装相同的 img 但 qemu 上的 -hda 选项没有/dev/ 中可用的高清。

这是我运行的命令。

./qemu-xilinx/arm-softmmu/qemu-system-arm -M xilinx-zynq-a9 -m 1024 -serial null -serial mon:stdio -dtb resources/devicetree.dtb -kernel resources/zImage -initrd resources.qemu/ramdisk.img -nographic -s

所以问题是：有没有办法避免联网，但在 qemu 和主机之间有一个共享目录？

编辑：我编译

./configure --target-list="arm-softmmu,microblazeel-softmmu" --enable-fdt --disable-kvm --enable-virtfs

这应该启用任何需要的东西。但是当我跑

./qemu-xilinx/arm-softmmu/qemu-system-arm -M xilinx-zynq-a9 -m 1024 -serial null -serial mon:stdio -dtb /homes/cperivol/Sandbox/xilinx-zynq-bootstrap/resources/devicetree.dtb -kernel /homes/cperivol/Sandbox/xilinx-zynq-bootstrap/resources/zImage -initrd /homes/cperivol/Sandbox/xilinx-zynq-bootstrap/resources.qemu/ramdisk.img -nographic -s -fsdev local,path=/homes/cperivol/Sandbox/xilinx-zynq-bootstrap/qemu-sandbox/,security_model=passthrough,id=host0 -device virtio-9p-pci,fsdev=host0,mount_tag=host_tag0

或者

./qemu-xilinx/arm-softmmu/qemu-system-arm -M xilinx-zynq-a9 -m 1024 -serial null -serial mon:stdio -dtb resources/devicetree.dtb -kernel resources/zImage -initrd resources.qemu/ramdisk.img -nographic -s -virtfs local,path=/homes/cperivol/Sandbox/xilinx-zynq-bootstrap/qemu-sandbox/,mount_tag=host0,security_model=passthrough,id=host0

我得到

No 'PCI' bus found for device 'virtio-9p-pci'

也许我还应该提到，在arm-softmmu/config-devices.mak那里CONFIG_PCI=y，果然 pci 的目标文件在hw/pci.

EDIT2：查看 qemu 转储的设备树，模拟系统不包括 PCI 总线。

(qemu) info qtree
bus: main-system-bus
  type System
  dev: xlnx.ps7-dev-cfg, id ""
    irq 1
    mmio 00000000f8007000/000000000000011c
  dev: pl330, id ""
    gpio-in 32
    num_chnls = 8
    num_periph_req = 4
    num_events = 16
    mgr_ns_at_rst = 0
    i-cache_len = 4
    num_i-cache_lines = 8
    boot_addr = 0
    INS = 0
    PNS = 0
    data_width = 64
    wr_cap = 8
    wr_q_dep = 16
    rd_cap = 8
    rd_q_dep = 16
    data_buffer_dep = 256
    irq 17
    mmio 00000000f8003000/0000000000001000
  dev: generic-sdhci, id ""
    capareg = 0x5780080
    maxcurr = 0x0
    irq 1
    mmio 00000000e0101000/0000000000000100
  dev: generic-sdhci, id ""
    capareg = 0x5780080
    maxcurr = 0x0
    irq 1
    mmio 00000000e0100000/0000000000000100
  dev: cadence_gem, id ""
    mac = 52:54:00:12:34:56
    vlan = 0
    netdev = hub0port0
    bootindex = -1
    irq 1
    mmio 00000000e000b000/0000000000000640
  dev: cadence_ttc, id ""
    irq 3
    mmio 00000000f8002000/0000000000001000
  dev: cadence_ttc, id ""
    irq 3
    mmio 00000000f8001000/0000000000001000
  dev: cadence_uart, id ""
    irq 1
    mmio 00000000e0001000/0000000000001000
  dev: cadence_uart, id ""
    irq 1
    mmio 00000000e0000000/0000000000001000
  dev: xlnx.ps7-qspi, id ""
    num-busses = 2
    num-ss-bits = 1
    num-txrx-bytes = 4
    irq 3
    mmio 00000000e000d000/0000000000000100
    mmio 00000000fc000000/0000000002000000
    bus: spi1
      type SSI
      dev: n25q128, id ""
        gpio-in 1
    bus: spi0
      type SSI
      dev: n25q128, id ""
        gpio-in 1
  dev: xlnx.ps7-spi, id ""
    num-busses = 1
    num-ss-bits = 4
    num-txrx-bytes = 1
    irq 5
    mmio 00000000e0007000/0000000000000100
    bus: spi0
      type SSI
      dev: n25q128, id ""
        gpio-in 1
      dev: n25q128, id ""
        gpio-in 1
      dev: n25q128, id ""
        gpio-in 1
      dev: n25q128, id ""
        gpio-in 1
  dev: xlnx.ps7-spi, id ""
    num-busses = 1
    num-ss-bits = 4
    num-txrx-bytes = 1
    irq 5
    mmio 00000000e0006000/0000000000000100
    bus: spi0
      type SSI
      dev: n25q128, id ""
        gpio-in 1
      dev: n25q128, id ""
        gpio-in 1
      dev: n25q128, id ""
        gpio-in 1
      dev: n25q128, id ""
        gpio-in 1
  dev: xlnx,ps7-usb, id "zynq-usb-1"
    maxframes = 128
    irq 1
    mmio 00000000e0003000/0000000000001000
    bus: zynq-usb-1.0
      type usb-bus
  dev: xlnx,ps7-usb, id "zynq-usb-0"
    maxframes = 128
    irq 1
    mmio 00000000e0002000/0000000000001000
    bus: zynq-usb-0.0
      type usb-bus
  dev: xlnx.ps7-i2c, id ""
    irq 1
    mmio 00000000e0005000/000000000000002c
    bus: i2c
      type i2c-bus
      dev: pca9548, id ""
        chip-enable = 0
        address = 0
        address-range = 128
        reg = 0
        bus: i2c@7
          type i2c-bus
        bus: i2c@6
          type i2c-bus
        bus: i2c@5
          type i2c-bus
        bus: i2c@4
          type i2c-bus
        bus: i2c@3
          type i2c-bus
          dev: at.24c08, id ""
            size = 1024
            address = 84
            address-range = 4
            reg = 84
          dev: at.24c08, id ""
            size = 1024
            address = 80
            address-range = 4
            reg = 80
        bus: i2c@2
          type i2c-bus
          dev: at.24c08, id ""
            size = 1024
            address = 84
            address-range = 4
            reg = 84
          dev: at.24c08, id ""
            size = 1024
            address = 80
            address-range = 4
            reg = 80
        bus: i2c@1
          type i2c-bus
        bus: i2c@0
          type i2c-bus
  dev: xlnx.ps7-i2c, id ""
    irq 1
    mmio 00000000e0004000/000000000000002c
    bus: i2c
      type i2c-bus
      dev: pca9548, id ""
        chip-enable = 0
        address = 0
        address-range = 128
        reg = 0
        bus: i2c@7
          type i2c-bus
        bus: i2c@6
          type i2c-bus
        bus: i2c@5
          type i2c-bus
        bus: i2c@4
          type i2c-bus
        bus: i2c@3
          type i2c-bus
          dev: at.24c08, id ""
            size = 1024
            address = 84
            address-range = 4
            reg = 84
          dev: at.24c08, id ""
            size = 1024
            address = 80
            address-range = 4
            reg = 80
        bus: i2c@2
          type i2c-bus
          dev: at.24c08, id ""
            size = 1024
            address = 84
            address-range = 4
            reg = 84
          dev: at.24c08, id ""
            size = 1024
            address = 80
            address-range = 4
            reg = 80
        bus: i2c@1
          type i2c-bus
        bus: i2c@0
          type i2c-bus
  dev: arm_mptimer, id ""
    num-cpu = 1
    irq 1
    mmio ffffffffffffffff/0000000000000020
    mmio ffffffffffffffff/0000000000000020
  dev: arm_mptimer, id ""
    num-cpu = 1
    irq 1
    mmio ffffffffffffffff/0000000000000020
    mmio ffffffffffffffff/0000000000000020
  dev: a9-scu, id ""
    num-cpu = 1
    irq 0
    mmio ffffffffffffffff/0000000000000100
  dev: arm_gic, id ""
    gpio-in 96
    num-cpu = 1
    num-irq = 96
    revision = 1
    irq 1
    mmio ffffffffffffffff/0000000000001000
    mmio ffffffffffffffff/0000000000000100
    mmio ffffffffffffffff/0000000000000100
  dev: a9mpcore_priv, id ""
    gpio-in 64
    num-cpu = 1
    num-irq = 96
    irq 1
    mmio 00000000f8f00000/0000000000002000
  dev: xilinx,zynq_slcr, id ""
    irq 0
    mmio 00000000f8000000/0000000000001000
  dev: nand, id ""
    manufacturer_id = 32
    chip_id = 170
    drive = <null>
    irq 0
  dev: cfi.pflash02, id ""
    drive = <null>
    num-blocks = 512
    sector-length = 131072
    width = 1
    mappings = 1
    big-endian = 0
    id0 = 102
    id1 = 34
    id2 = 0
    id3 = 0
    unlock-addr0 = 2730
    unlock-addr1 = 1365
    name = "pl353.pflash"
    irq 0
    mmio ffffffffffffffff/0000000004000000
  dev: arm.pl35x, id ""
    x = 3
    irq 0
    mmio 00000000e000e000/0000000000001000
    mmio 00000000e2000000/0000000001000000
    mmio 00000000e1000000/0000000001000000

Answer 1

如果来宾支持 9p（例如 Linux，当然还有 Plan 9）和 virtio，请尝试添加以下开关。

-virtfs local,path=/path/to/share,mount_tag=host0,security_model=passthrough,id=host0

您可能想要更改 security_model 参数。请参见手册页 qemu(1)。如果我没记错的话， mount_tag 是客人看到的，将 id 留作假人。

如果您正在 chroot，请确保路径在 chroot 下。它是主机上目录的路径。

来宾上的 fstab 条目应如下所示。

host0   /wherever    9p      trans=virtio,version=9p2000.L   0 0

要么将它添加到您的 fstab，要么手动调用适当的命令或使用您的 init 系统，无论它是什么。

Answer 2

适用于 x86_64、arm 和 aarch64 的极简工作 9P Buildroot 设置

我创建了一个高度自动化的 Buildroot 工作设置，它可能会帮助您区分为什么您的方法不起作用。

主要成分是：

• 内核设置：

  CONFIG_9P_FS=y
  CONFIG_9P_FS_POSIX_ACL=y
  CONFIG_9P_FS_SECURITY=y
  CONFIG_NETWORK_FILESYSTEMS=y
  CONFIG_NET_9P=y
  CONFIG_NET_9P_DEBUG=y
  CONFIG_NET_9P_VIRTIO=y
  

  对于 aarch64，还要添加：

  CONFIG_PCI=y
  CONFIG_PCI_HOST_COMMON=y
  CONFIG_PCI_HOST_GENERIC=y
  CONFIG_VIRTIO_PCI=y
  CONFIG_VIRTIO_BLK=y
  CONFIG_VIRTIO_NET=y
  

  如果您忘记添加 aarch64 配置并mount失败：

  mount: mounting host0 on /mnt/my9p failed: Invalid argument
  

  和 dmesg 抱怨：

  9pnet_virtio: no channels available for device
  

  记录在：https : //wiki.qemu.org/Documentation/9psetup

• 我的 fstab 条目和 QEMU 命令与在以下位置解释的完全一样：https : //superuser.com/a/628381/128124

  手动挂载命令为：

  mkdir /mnt/my9p
  mount -t 9p -o trans=virtio,version=9p2000.L host0 /mnt/my9p
  

  host0QEMU CLI 上指定的标签在哪里。

  作为参考，我完整的 QEMU 命令行是：x86：

  ./buildroot/output.x86_64~/host/usr/bin/qemu-system-x86_64 \
  -m 128M \
  -monitor telnet::45454,server,nowait \
  -netdev user,hostfwd=tcp::45455-:45455,id=net0 \
  -smp 1 \
  -virtfs local,path=/host/path/to/share,mount_tag=host0,security_model=mapped,id=host0  \
  -M pc \
  -append 'root=/dev/vda nopat nokaslr norandmaps printk.devkmsg=on printk.time=y' \
  -device edu \
  -device lkmc_pci_min \
  -device virtio-net-pci,netdev=net0 \
  -kernel ./buildroot/output.x86_64~/images/bzImage    \
  -drive file='./buildroot/output.x86_64~/images/rootfs.ext2.qcow2,if=virtio,format=qcow2'
  

  手臂：

  ./buildroot/output.arm~/host/usr/bin/qemu-system-arm -m 128M -monitor telnet::45454,server,nowait -netdev user,hostfwd=tcp::45455-:45455,id=net0 -smp 1 -virtfs local,path=/host/path/to/share,mount_tag=host0,security_model=mapped,id=host0  -M versatilepb -append 'root=/dev/sda nokaslr norandmaps printk.devkmsg=on printk.time=y' -device rtl8139,netdev=net0 -dtb ./buildroot/output.arm~/images/versatile-pb.dtb -kernel ./buildroot/output.arm~/images/zImage -serial stdio    -drive file='./buildroot/output.arm~/images/rootfs.ext2.qcow2,if=scsi,format=qcow2' 
  

  aarch64：

  ./buildroot/output.aarch64~/host/usr/bin/qemu-system-aarch64 -m 128M -monitor telnet::45454,server,nowait -netdev user,hostfwd=tcp::45455-:45455,id=net0 -smp 1 -virtfs local,path=/host/path/to/share,mount_tag=host0,security_model=mapped,id=host0  -M virt -append 'root=/dev/sda nokaslr norandmaps printk.devkmsg=on printk.time=y' -cpu cortex-a57 -device virtio-net-device,netdev=net0 -kernel ./buildroot/output.aarch64~/images/Image -nographic -serial stdio    
  

在 QEMU 2.11 和来宾 Linux 内核 4.15 上测试。

然后我还在 Ubuntu 18.04 上进行了测试，它刚刚工作：https : //askubuntu.com/questions/884534/how-to-run-ubuntu-desktop-on-qemu/1046792#1046792