A key characteristic of the Qcow2 format is that it uses a sparse representation. This means the initial .qcow2 file is very small and only grows as new data is written to the virtual disk. This is a significant advantage over the "raw" format, which pre-allocates the entire virtual disk size from the start.
qemu-system-i386 -hda winxp.qcow2 -cdrom winxp_iso_name.iso -boot d -enable-kvm -cpu host -m 512 -vga cirrus -net nic,model=rtl8139 -net user -usbdevice tablet -localtime i--- Windows Xp Qcow2
Ensure your hardware supports virtualization extensions (Intel VT-x or AMD-V) and that they are enabled in your BIOS/UEFI settings. A key characteristic of the Qcow2 format is
If you're planning to use Windows XP Qcow2, keep in mind: qemu-system-i386 -hda winxp
The rtl8139 driver usually works out of the box, but virtio-net is faster if you add the driver during installation. 2. Improving Network Performance