Virtualbox is a good virtual machine that is compatible with multiple platforms, such as Windows, Linux, and MAC systems. It can also be used to virtualize many types of systems. My laptop has two systems: wiin7 and Ubuntu, but I only installed virtualbox on ubutnu. Sometimes I need to use a virtual machine when I start Windows 7. If I have a vmvirtual machine, it's a lot of trouble to install a system in a virtual machine! Finally, I came up with a perfect solution. Both Windows 7 and Ubuntu use virtualbox and share a virtual hard disk (suffix. VDI). This solved the problem perfectly.
However, Windows 7 does not support ext4 file systems. It is impossible to copy a virtual hard disk in Ubuntu to a partition in NTFS format, because each VDI uses a unique UUID and can only be copied using the tool that comes with virtualbox, The vboxmanage command is as follows: vboxmanage clonevdi path/original VDI file name path/New VDI file name → press enter to clone the same virtual disk. You only need to create a new virtual system and then load the virtual hard disk. I personally think that the system in the virtual machine needs to be used in many ways, and the random power failure is not easy to break down. If your CPU supports hardware virtual VT-X, the running speed is similar to that of the native installation system.