Virtiofs

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Resources

virtiofs is a shared file system that lets virtual machines access a directory tree on the host.

Installation

USE flags

USE flags for app-emulation/virtiofsd Shared file system for virtual machines

debug Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces

Data provided by the Gentoo Package Database · Last update: 2024-10-11 02:28 More information about USE flags

Emerge

root #emerge --ask app-emulation/virtiofsd

Usage

Start virtiofsd with the relevant shared directory, and a path to be used as a socket:

user $SHARED_DIR=/home/user/share/

user $SOCKET_PATH=/tmp/vhostqemu

user $/usr/libexec/virtiofsd --shared-dir "${SHARED_DIR}" --socket-path "${SOCKET_PATH}" --cache auto

QEMU VMs

The guest VM needs to be running the Linux kernel, version 5.4 or later, with the CONFIG_VIRTIO_FS kernel configuration option enabled.

Start QEMU with your preferred options, plus the following:

-chardev socket,id=char0,path="${SOCKET_PATH}"
-device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=VHOST_TAG
-object memory-backend-file,id=mem,size=MEM_SIZE,mem-path=/dev/shm,share=on -numa node,memdev=mem

where VHOST_TAG is an arbitrary name (e.g. myfs) that will be used with a mount(8) command inside the guest, and MEM_SIZE is the memory size you specified with the -m option.

Once logged in on the guest as root, mount the virtiofs using the VHOST_TAG specified when starting QEMU:

root #mount -t virtiofs myfs /mnt

The contents of SHARED_DIR should now be available in the /mnt directory.