Wiki QEMU

Learning and using the QEMU help me understand how the linux operating system works including fields:

Linux boot process.
Cross compile for target system(such as arm64) on host system(such as x86_64), and test the binary.

OS image Resources

QEMU Keyboard shortcuts

Switch between QEMU monitor console and the guest non-graphic OS
- CTRL+a c
Exit the guest non-graphic OS
- CTRL+a x
Switch between QEMU monitor console and the guest graphic OS
- CTRL+ALT+1, CTRL+ALT+2

Discover the VM device tree

Enter the QEMU monitor console, using info qtree command,

$ info qtree

 dev: gpex-pcihost, id ""
    ...
    bus: pcie.0
      type PCIE
      dev: virtio-scsi-pci, id ""
        ...
        bus: virtio-bus
          type virtio-pci-bus
          dev: virtio-scsi-device, id ""
            ...
            bus: scsi.0
              type SCSI
              dev: scsi-hd, id ""
                drive = "hd"
                ...
      dev: nvme, id ""
        drive = "drive0"
        ...
        bus: nvme-bus.0
          type nvme-bus
      dev: virtio-net-pci, id ""
        ...
        bus: virtio-bus
          type virtio-pci-bus
          dev: virtio-net-device, id ""
            ...

List supported devices

$ qemu-system-aarch64 -device help
$ qemu-system-aarch64 -device scsi-hd,help

Create disk image

qemu-img create -f raw ubuntu.raw 20G
qemu-img create -f qcow2 ubuntu.qcow2 20G

QEMU can boot from 3 ways:

BIOS in default
Linux kernel and initrad
UEFI

For UEFI boot, the -bios option should be used alongside UEFI firmware(OVMF.fd file) being provided to help QEMU do UEFI boot. For instance it is like: -bios OVMF.fd.

Get a prebuilt OVMF file from the OVMF.

BIOS boot

Test entering BIOS,

qemu-system-x86_64 -monitor stdio -m 1G

Then QEMU will show like this,

Kernel boot

UEFI boot

Test UEFI boot

aarch64,

efi="$PWD/UEFI/aarch64/QEMU_EFI.fd"

qemu-system-aarch64 -monitor stdio -M virt -cpu cortex-a57 -m 1G -net none -bios $efi

qemu-system-aarch64 -nographic -M virt -cpu cortex-a57 -m 1G -net none -bios $efi

x86_64,

efi="$PWD/UEFI/ovmf-x64/OVMF-pure-efi.fd"

qemu-system-x86_64 -monitor stdio -m 1G -net none -bios $efi

Then QEMU will drop into the UEFI shell, like this following image show,

efi

Options in detail:

-nographic: Don't create a video for the VM, just use the terminal.

info

quit QEMU: Ctrl+A X.
enter QEMU monitor console: Ctrl+A C.
see at How to quit the QEMU monitor when not using a GUI?

-monitor stdio: Put QEMU monitor console in the terminal, while guest OS kept in created video device.

info

switch between monitor console and guest OS: Ctrl+Alt+1 or Ctrl+Alt+2.

-net none: Disable iPXE.

Boot x86_64 ISO image

Boot x86_64 image in Windows,

efi="$PWD/UEFI/ovmf-x64/OVMF-pure-efi.fd"
iso=ubuntu-22.04-live-server-amd64.iso

note

ubuntu-**-amd64.iso support both UEFI and Legacy BIOS boot, QEMU use BIOS when the option -bios is not specified!

Create a disk image to install the ubuntu OS,

qemu-img create -f qcow2 ubuntu-image.qcow2 20G

Boot to run the Ubuntu OS

qemu-system-x86_64 \
    -monitor stdio \
    -accel whpx \
    -m 8G \
    -smp 4 \
    -drive file=ubuntu-image.qcow2 \
    -bios $efi \
    -cdrom $iso

Options in details,

-accel whpx: use hardware acceleration

[?]Boot the installed Ubuntu OS

# Install OS into a disk image
qemu-system-x86_64 \
    -accel whpx \
    -m 8G \
    -smp 4 \
    -bios $efi \
    -drive file=ubuntu.qcow2,format=qcow2,if=virtio \

Boot aarch64 ISO image

Emulate aarch64 ISO image in Windows,

efi="$PWD/UEFI/aarch64/QEMU_EFI.fd"
iso="ubuntu-22.04-live-server-arm64.iso"

qemu-system-aarch64 \
    -monitor stdio \
    -machine virt \
    -cpu cortex-a57 \
    -m 4G \
    -smp 4 \
    -drive file=ubuntu.qcow2,format=raw,if=virtio \
    -bios $efi \
    -cdrom $iso

Emulate aarch64 ISO image in mac M1,

qemu-system-aarch64 \
    -monitor stdio \
    -machine virt \
    -accel hvf \
    -cpu host \
    -m 4G \
    -smp 4 \
    -drive file=ubuntu.qcow2,format=raw,if=virtio \
    -bios $efi \
    -cdrom $iso

Options in details,

-accel hvf: use hardware acceleration in mac M1.
-cpu host: use mac M1 arm CPU.

Boot a preinstalled image

# linux
fdisk -l ubuntu-core-22-arm64+raspi.img

# osx
hdiutil imageinfo ubuntu-core-22-arm64+raspi.img

kernel="$PWD/TinyCore/boot/vmlinuz64"
initrd=$"$PWD/TinyCore/boot/corepure64.gz"
img=$"$PWD/TinyCorePure64-14.0.iso"
efi="$PWD/UEFI/ovmf-x64/OVMF-pure-efi.fd"

kernel="$PWD/linux_qemu/x86_64/bzImage"
vmlinuz="$PWD/linux_qemu/x86_64/vmlinux"
initrd="$PWD/linux_qemu/x86_64/rootfs.ext2"
img="$PWD/linux_qemu/x86_64/rootfs.ext2"

qemu-system-x86_64 \
    -nographic \
    -m 4G \
    -kernel $kernel \
    -initrd $img \
    -append "console=ttyS0" \
    -netdev user,id=mynet,hostfwd=tcp::2222-:22 \
    -device virtio-net-pci,netdev=mynet