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Multipass has simple commands and options to share Windows directories with Multipass VMs. This is done through the multipass mount command after the VM is created, or the --mount parameter when creating a VM. This is, however, one of the places where the authors opted first for something they could get to work the same way on all systems without regard to performance. They use a terribly inefficient tool that shares directories over an SSH connection. This is fine for casual access to files, but not for anything that does a lot of I/Ofile system based on SSH that provides very poor performance.
If you need to do more than casual file transfer, you need something better. There are other options (NFS, CIFS - a.k.a. Windows Shares, …). I will update this if anyone proposes a best practice .This is one of the places where a multi-user machine would have problems with security. Mounts are shipped disabled, and if you are running on a single user environment or you trust all your usersor posts some benchmarks.
Hyper-V bypasses Windows access control, and Multipass runs as a background service under a SYSTEM userid. There is no way to recreate file system access control. The multipass mount service is shipped disabled, and you have to turn it on as an administrator. After that, you acknowledge that directories are being exposed to everyone, which is why this is best done on a single user machine. To turn mounts on, open a Run as Administrator command prompt window and issue the one time command:
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