Skip to content

Latest commit

 

History

History
231 lines (165 loc) · 5.42 KB

readme.md

File metadata and controls

231 lines (165 loc) · 5.42 KB

qemu

Installation or Removal (apt)

Installation

sudo apt install qemu-system

Removal

  • To remove all qemu things
for p in $(apt list --installed 2>/dev/null | grep 'qemu' | cut -d'/' -f1); do sudo apt remove -y $s; done

Create Image

Template Command

qemu-img create -f qcow2 <IMAGE_NAME> <SIZE>

Example

qemu-img create -f qcow2 obsd.img 20G

Initial Boot

Template Command

qemu-system-x86_64 -m <RAM_MEMORY_SIZE> -enable-kvm -drive file=<IMAGE_NAME> -cdrom <DISTRO_ISO_FILE> -boot order=d -display sdl,gl=on

Example

qemu-system-x86_64 -m 1G -enable-kvm -drive file=obsd.img -cdrom openbsd-install73.iso -boot order=d -display sdl,gl=on
  • Need -cdrom <ISO> for Initial Boot into desired iso

Boot (after initial boot)

Example

qemu-system-x86_64 -enable-kvm -boot menu=on \
		   -drive file=obsd.img -m 8G -vga virtio \
		   -usb -device usb-tablet \
		   -display sdl,gl=on

Snapshot

Listing Snapshots

# Template
# qemu-img snapshot -l <IMAGE>

qemu-img snapshot -l obsd.img

Adding a snapshot

# Template
# qemu-img snapshot -c <SNAPSHOT> <IMAGE>

qemu-img snapshot -c snap1 obsd.img

Reverting to a Snapshot

# Template
# qemu-img snapshot -a <SNAPSHOT> <IMAGE>

qemu-img snapshot -a snap1 obsd.img

Deleting a Snapshot

# Template
# qemu-img snapshot -d <SNAPSHOT> <IMAGE>

qemu-img snapshot -d snap1 obsd.img

Resizing an image

# template
# qemu-img resize <img> <new_size>

qemu-img resize obsd.img 30G

Networking

qemu-system-x86_64 -enable-kvm -boot menu=on \
		   -drive file=obsd.img -m 8G -vga virtio \
		   -usb -device usb-tablet \
		   -display sdl,gl=on \
           -device e1000,netdev=net0 \ 
           -netdev user,id=net0,hostfwd=tcp::5555-:22
           
# To Connect, ensure the vm has ssh service on and then you can ssh into the qemu vm:
# > ssh <qemu-user>@localhost -p 5555
  • By default, the gateway router is the host machine

To list supported NIC models

qemu-system-x86_64 -nic model=help

Cores that VM can use

  • To check the number of cores, you can use the following commands:
    • linux: nproc
    • darwin, bsd: sysctl -n hw.ncpu
    • other: getconf _NPROCESSORS_ONLN

Template

qemu-system-x86_64 -m <RAM_MEMORY_SIZE> -enable-kvm -cpu <CPU>  -smp <CORES> -drive file=<IMAGE_NAME> -cdrom <DISTRO_ISO_FILE> -boot order=d -display sdl,gl=on

Example

qemu-system-x86_64 -m 1G -enable-kvm -cpu host -smp 4 -drive file=obsd.img -cdrom openbsd-install73.iso -boot order=d -display sdl,gl=on

# alternatively can use something like this
qemu-system-x86_64 -m 1G -enable-kvm -cpu host -smp $(echo "$(nproc)//2" | bc | cut -d'.' -f1) -drive file=obsd.img -cdrom openbsd-install73.iso -boot order=d -display sdl,gl=on

Resources

Qemu Monitor

Sending Keys to VM

  • Sometimes you might need to send keys to the computer for certain functionality, it must be done via compatmonitor0
ctrl+alt+2

# ctrl-alt+f2 at login (on *nix), will force someone to work with terminal/text-based login/tty thing
# Within `compatmonitor0`, type:
(qemu) sendkey ctrl+alt+f2

# To switch back to `virtio-vga`, do:
ctrl+alt+1

Snapshots

# Check existing snapshots

(qemu) info snapshots

# Create new snapshots
# template:
# (qemu) savevm <name>

(qemu) savevm new-test

# Load snapshots
# template:
# (qemu) loadvm <name>

(qemu) loadvm new-test

Device Passthrough

USB stick

  • First check lsusb, usbdevs on openbsd. Might look something like this:
Bus 001 Device 003: ID 1111:aaaa -------- SOMETHING ---------
Bus 002 Device 004: ID 2222:cccc -------- SOMETHING ---------
Bus 003 Device 054: ID 3333:dddd          USB DISK
Bus 004 Device 123: ID 4444:ffff -------- SOMETHING ---------
...

  • Shell Script usb-devices provides a lot more in depth knowledge about usb devices connected (as well as drivers)

  • Let's say we want to pass-through the USB DISK, entry, the following might look like this:

# template 
cat << 'EOF
qemu-system-x86_64 -enable-kvm -boot menu=on \
		   -drive file=obsd.img -m 8G -vga virtio \
		   -display sdl,gl=on \
           -drive if=none,id=stick,format=raw,file=<.IMG file path> \
           -device nec-usb-xhci,id=xhci \
           -device usb-storage,bus=xhci.0,drive=stick \
           -usb -device usb-host,hostbus=<BUS ADDR>,hostaddr=<DEVICE ADDR>
EOF

qemu-system-x86_64 -enable-kvm -boot menu=on \
		   -drive file=obsd.img -m 8G -vga virtio \
		   -display sdl,gl=on \
           -drive if=none,id=stick,format=raw,file=/tmp/miniroot74.img \
           -device nec-usb-xhci,id=xhci \
           -device usb-storage,bus=xhci.0,drive=stick \
           -usb -device usb-host,hostbus=003,hostaddr=054

Replaying/Recording

  • -icount is not allowed with hardward virtualization, thus -enable-kvm flag (to boost speed) can't be invoked