How share folder in QEMU with plan9/virtfs between MacOS host and Linux guest?

Question

I am trying to run a Linux Debian with qemu with MacOS Big Sur host.

Unfortunately virtfs doesn't work on Mac and there is no easy alternative that I have found.

Is there a way to share folders with plan9?

Thanks!!

EDIT:

This is what I need: https://github.com/NixOS/nixpkgs/pull/122420 but it is still in progress !!

Thanks to all!

Answer 1

As of March 2022, 9pfs is available in QEMU on macOS if you're using homebrew. My qemu-system-x86_64 command includes the following parameter:

-virtfs local,path=/Users/gsf/Downloads,security_model=none,mount_tag=Downloads

And my /etc/fstab in the guest includes this line:

Downloads /home/gsf/Downloads 9p _netdev,trans=virtio,version=9p2000.u,msize=104857600 0 0

With security_model=none I did have to modify user and group IDs in the guest to match the host. You may prefer security_model=mapped instead.

Also I tried version=9p2000.L but that resulted in "Network dropped connection on reset" errors when trying to access the shared directory. For more info on my full setup, see my Ubuntu VM on macOS with QEMU.

For a documentation of 9pfs from QEMU, visit here.

Answer 2

As of July 2021, 9pfs and virtfs are not available in QEMU on macOS.

An alternate method to share folders with read-write access from a macOS host to a Linux VM is to use sshfs.

Read-write access using SSHFS

1. Install sshfs on Linux VM.
2. Allow remote login on macOS host: System Preferences > Sharing > Remote login.
3. Mount macOS directory on Linux VM via:

sshfs user@macos_ip:/Users/user/mydir ~/host_mydir

If you cannot use ssh to access the macOS host you can still share the directory with read-only access using QEMU virtual FAT disk images:

Read-only access using a virtual FAT disk image

1. Add directory as a disk image via:

Note: VM will not start without fat:rw:

qemu-system-x86_64 \
  -machine type=q35,accel=hvf \
  -cpu host \
  -hda /images/linux.qcow2 \
  -drive file=fat:rw:/Users/user/mydir,format=raw,media=disk

2. Mount directory in Linux VM via:

Note: directory will not mount without -o ro

# 'ro' is required to mount directory
sudo mount -t auto -o ro /dev/sdb1 /media

This method has some limitations:

• [never] use non-ASCII filenames
• [never] use “-snapshot” together with “:rw:”
• [never] expect it to work when loadvm’ing
• [never] write to the FAT directory on the host system while accessing it with the guest system

Answer 3

This is what I need: https://github.com/NixOS/nixpkgs/pull/122420

Thanks to all!