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[Question]: How can I share a folder from my host system with a guest virtual machine running in QEMU ?
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Question
Hi,
I would like to share a folder from my host system with a guest virtual machine running in QEMU. I’ve been trying to find the right way to do this, but I haven’t been able to get it to work. Could you please provide a step-by-step guide on how to properly share a host folder with a guest VM?
Specifically, I tried using the following command:
volumes:
- /media/lvm/backup/Roon-Backups:/data/storage/bck:rw
Could you please guide me on how to correctly set up folder sharing between the host and the guest? Any help would be greatly appreciated!
Thank you!
could you tell how you are trying to achieve this? (Network sharing or just sharing offline?)
could you tell how you are trying to achieve this? (Network sharing or just sharing offline?)
Sure! My idea is to use your fantastic project to run “Roon-Server.” You can check it out here: https://roon.app/. More specifically, the image to download is this one: https://download.roonlabs.net/builds/roonbox-linuxx64-nuc4-usb-factoryreset.img.gz. It is listed in this guide, section 3 “Download”: https://help.roonlabs.com/portal/en/kb/articles/rock-install-guide#3_Download.
In short, this is audio software for listening to music. My music is stored on a partition on my host, and the backup folder (which the application interacts with for regular backups) is also on a partition on my host. I would like to be able to pass these two directories (for example, /media/lvm/data/Music and /media/lvm/backup) to the virtual machine.
Might there be some way to use QEMU's 9pfs to achieve this?
yes but how? i tried but always nothing comes from host to guest
The way I am doing this is:
- Ensure that your guest has 9pfs support compiled in or available as a kernel module
- Add a volume in docker-compose.yml so that qemu will have access to your host's FS via a bind mount:
volumes:
- /mnt/shared:/mnt/shared
- Add an ARGUMENT parameter to the environment section of docker-compose.yml:
environment:
ARGUMENTS: "-fsdev local,id=fsdev0,path=/mnt/shared,security_model=none -device virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=host_share"
- Boot the guest and then attempt to mount the shared location:
mount -t 9p -o trans=virtio host_share /mnt/guest_mountpoint
I have just tested this and it appears to work as expected.
@fizzyduck It's now added to the readme, thank you! Please verify if it works: https://github.com/qemus/qemu#how-do-i-share-files-with-the-host
@kroese I just got round to testing this per your readme but I notice the readme misses an instruction to ensure that the ARGUMENTS compose parameter has the relevant additions:
-fsdev local,id=fsdev0,path=/mnt/shared,security_model=none -device virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=host_share
Noting that the fsdev portion related to the volume entry and the device portion sets up the tag (in this case host_share) which must be used in the mount command.
For your readme example, you would need:
ARGUMENTS: "-fsdev local,id=fsdev0,path=/shared,security_model=none -device virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=shared"
Note the volume from the compose config (/shared) and the name to be used in the mount command (shared).
@fizzyduck I added in the code that when it detects the /shared folder it automaticly adds those lines: https://github.com/qemus/qemu/blob/0944104d5589ba8906c17b21f56395d2eb548f36/src/config.sh#L26
So no ARGUMENTS should be needed at all.
@kroese I just had a hunch you'd probably do that and went and looked at the PR to then notice you had already taken care of this - I've obviously not pulled the latest version! Apologies for that.