1. 下载并安装qemu

1. 下载

git clone https://gitlab.com/qemu-project/qemu.git

2. 安装

#!/bin/bash




rm -rf build
mkdir build
cd build


sudo apt-get install build-essential zlib1g-dev pkg-config libglib2.0-dev binutils-dev libboost-all-dev autoconf libtool libssl-dev libpixman-1-dev libpython2-dev python3-pip python-capstone virtualenv

git submodule init
git submodule update --recursive

../configure --target-list=x86_64-softmmu

make -j`nproc`

下载 cloud image 并 在 qumu 中进行运行

script 一键运行

#!/usr/bin/env bash

sudo apt-get install cloud-image-utils qemu

# This is already in qcow2 format.
img=ubuntu-18.04-server-cloudimg-amd64.img
if [ ! -f "$img" ]; then
  wget "https://cloud-images.ubuntu.com/releases/18.04/release/${img}"

  # sparse resize: does not use any extra space, just allows the resize to happen later on.
  # https://superuser.com/questions/1022019/how-to-increase-size-of-an-ubuntu-cloud-image
  qemu-img resize "$img" +128G
fi

user_data=user-data.img
# For [ ! -f "$user_data" ] syntax
# https://linuxize.com/post/bash-check-if-file-exists/
if [ ! -f "$user_data" ]; then
  # For the password.
  # https://stackoverflow.com/questions/29137679/login-credentials-of-ubuntu-cloud-server-image/53373376#53373376
  # https://serverfault.com/questions/920117/how-do-i-set-a-password-on-an-ubuntu-cloud-image/940686#940686
  # https://askubuntu.com/questions/507345/how-to-set-a-password-for-ubuntu-cloud-images-ie-not-use-ssh/1094189#1094189
  # How does "cat << EOF" work in bash?
  # https://stackoverflow.com/questions/2500436/how-does-cat-eof-work-in-bash
  cat >user-data <<EOF
#cloud-config
password: asdfqwer
chpasswd: { expire: False }
ssh_pwauth: True
EOF
  cloud-localds "$user_data" user-data
fi

qemu-system-x86_64 \
  -drive "file=${img},format=qcow2" \
  -drive "file=${user_data},format=raw" \
  -device rtl8139,netdev=net0 \
  -enable-kvm \
  -m 2G \
  -netdev user,id=net0 \
  -serial mon:stdio \
  -smp 2 \
  -vga virtio \
;

qemu-system-x86_64 -enable-kvm -hda /tmp/vm00.qcow2 -kernel /var/tmp/vmlinuz-5.7.0-050700-generic -nographic -m 1024 -object memory-backend-uswap,size=1073741824,id=m0,allocator=hugetlb -numa node,memdev=m0 -append 'console=ttyS0 root=/dev/sda1'

使用 libvirt 启动虚拟机的常用命令

1. 查看 cloud image 的信息

/usr/bin/qemu-img info ubuntu-20.04-minimal-cloudimg-amd64.img
image: /var/local/uswap-benchmark/ubuntu-20.04-minimal-cloudimg-amd64.img
file format: qcow2
virtual size: 2.2 GiB (2361393152 bytes)
disk size: 1.23 GiB
cluster_size: 65536
Format specific information:
    compat: 0.10
    refcount bits: 16

2. 拷贝 base cloud imageubuntu-20.04-minimal-cloudimg-amd64.img 到其他地方 作为 disk

qemu-img create -f qcow2 -b ubuntu-20.04-minimal-cloudimg-amd64.img -F /path/to/other/place/000-ubuntu-20.04-minimal-cloudimg-amd64.img

3. 定义一个 虚拟机的 配置文件 vm.xml

4. define a domain

sudo /usr/local/bin/virsh define vm.xml

5. start a domain/vm

sudo /usr/local/bin/virsh start {domain_name}

6. Output a guest’s XML configuration file with virsh:
   This command outputs the guest’s XML configuration file to standard out (stdout).

virsh dumpxml {guest-id, guestname or uuid}

EXAMPLE OUTPUT:

# virsh dumpxml guest1-rhel6-64
<domain type='kvm'>
  <name>guest1-rhel6-64</name>
  <uuid>b8d7388a-bbf2-db3a-e962-b97ca6e514bd</uuid>
  <memory>2097152</memory>
  <currentMemory>2097152</currentMemory>
  <vcpu>2</vcpu>
  <os>
    <type arch='x86_64' machine='rhel6.2.0'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='none' io='threads'/>
      <source file='/home/guest-images/guest1-rhel6-64.img'/>
      <target dev='vda' bus='virtio'/>
      <shareable/<
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>
    <interface type='bridge'>
      <mac address='52:54:00:b9:35:a9'/>
      <source bridge='br0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='-1' autoport='yes'/>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </sound>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>
  </devices>
</domain>

• Here we can find the mac address of the VM (devices->interface->mac)

7. 找到 与 mac 对应 的虚拟机 ip 地址

sudo /usr/local/bin/virsh net-dhcp-leases default

8. 使用ssh 控制虚拟机 执行命令 remot_cmd

ssh -o StrictHostKeyChecking=no user_name_in_vm@vm_ip -i path/to/private_key_on_host  remot_cmd

9. 显示正在运行的 虚拟机

sudo /usr/local/bin/virsh list

10. kill 一个虚拟机

sudo /usr/local/bin/virsh destroy {domain_name}

11. undefine a domain

sudo /usr/local/bin/virsh undefine domain_name

12 copy file into vm disk image

sudo virt-copy-in -a /tmp/vm00.qcow2 /lib/modules/$(uname -r) /lib/modules/

13 copy file out of a vm disk image

virt-copy-out - Copy files and directories out of a virtual machine disk image.

more detail

14. some more command to resize the disk ,etc.

qemu-img resize vm3.qcow2 100G

lsblk

df -h

sudo growpart /dev/sda 3

sudo resize2fs /dev/sda1 SIZE

15. libvirt working template

<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  <name>qemu-yaoxin</name>
  <memory unit="G">32</memory>
  <vcpu>8</vcpu>
  <cpu mode='host-model'>
    <numa>
      <cell id='0' cpus='0-7' memory='32' unit='G'/>
    </numa>
  </cpu>
  <os>
    <type arch='x86_64' machine='pc'>hvm</type>
  </os>
  <memoryBacking>
  </memoryBacking>
  <devices>
    <emulator>/home/yaoxin/code/local/bin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='unsafe'/>
      <source file='/home/yaoxin/memcached-disk-image/vm3.qcow2'/>
      <target dev='vda' bus='ide'/>
    </disk>
    <interface type='bridge'>
      <source bridge='virbr0'/>
      <model type='virtio'/>
    </interface>
    <console type='pty'>
      <target type='serial'/>
    </console>
    <console type='pty'>
      <target type='virtio'/>
    </console>
    <rng model='virtio'>
      <backend model='random'/>
    </rng>
  </devices>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>destroy</on_reboot>
  <on_crash>destroy</on_crash>
  <features>
    <acpi />
  </features>
<qemu:commandline>
  <qemu:arg value='-drive'/>
  <qemu:arg value='file=/home/yaoxin/vm-nvme/nvme.qcow2,format=qcow2,if=none,id=NVME1'/>
  <qemu:arg value='-device'/>
  <qemu:arg value='nvme,drive=NVME1,serial=nvme-1'/>
</qemu:commandline>

</domain>