### Build and Install Linux Kernel

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Build and install the configured Linux kernel and its modules within the guest VM. This process ensures the kernel is ready for use.

```bash
make -j 8 && make -j 8 modules && make -j 8 modules_install && make -j 8 install
```

--------------------------------

### Register and start the virtiofs service

Source: https://virtio-fs.gitlab.io/howto-windows.html

Commands to register the virtiofs service with automatic startup and initiate the service.

```cmd
C:\> sc.exe create VirtioFsSvc binpath="(your binary location)\virtiofs.exe" start=auto depend="WinFsp.Launcher/VirtioFsDrv" DisplayName="Virtio FS Service"
```

```cmd
C:\> sc start VirtioFsSvc
```

--------------------------------

### Start virtiofs daemon

Source: https://virtio-fs.gitlab.io/howto-boot.html

Launches the virtiofsd daemon to manage the shared directory socket.

```bash
# virtiofsd --socket-path=/tmp/vhostqemu -o source=virtio-fs-root -o cache=none
```

--------------------------------

### Start virtiofsd Daemon

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Run the virtiofsd daemon, specifying the socket path and source directory for the shared filesystem. Cache options can also be set.

```bash
/usr/libexec/virtiofsd --socket-path=/tmp/vhostqemu -o source=$TESTDIR -o cache=always
```

--------------------------------

### Clone QEMU for virtiofs Development

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Clone the QEMU repository if you need to build it from source for development purposes, particularly for modifying vhost-user-fs device setup.

```bash
git clone https://gitlab.com/qemu-project/qemu.git
```

--------------------------------

### Configure and Build QEMU

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Configure QEMU with the specified target list and build it. This step is typically needed for development or if a specific version is required.

```bash
../configure --prefix=$PWD --target-list=x86_64-softmmu
make -j 8
```

--------------------------------

### QEMU Device Instantiation for virtiofs

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Instantiate the vhost-user-fs-pci device in QEMU, linking it to the defined character device and setting a tag that must match the guest's mount command.

```bash
-device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs
```

--------------------------------

### Full QEMU Command for virtiofs

Source: https://virtio-fs.gitlab.io/howto-qemu.html

A complete QEMU command line to launch a VM with virtiofs enabled, including memory sharing, the virtiofs device, and a root filesystem image.

```bash
qemu-system-x86_64 -M pc -cpu host --enable-kvm -smp 2 \
     -m 4G -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on -numa node,memdev=mem \
     -chardev socket,id=char0,path=/tmp/vhostqemu -device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs \
     -chardev stdio,mux=on,id=mon -mon chardev=mon,mode=readline -device virtio-serial-pci -device virtconsole,chardev=mon -vga none -display none \
     -drive if=virtio,file=rootfsimage.qcow2
```

--------------------------------

### Create Fedora root file system

Source: https://virtio-fs.gitlab.io/howto-boot.html

Initializes a directory to serve as the root file system for the guest.

```bash
# mkdir virtio-fs-root
# dnf --installroot=$PWD/virtio-fs-root --releasever=29 install system-release vim-minimal systemd passwd dnf rootfiles
# $EDITOR virtio-fs-root/etc/shadow # set password or allow password-less root login
```

--------------------------------

### Set QEMU kernel parameters

Source: https://virtio-fs.gitlab.io/howto-boot.html

Defines the root file system type and mount options for the guest kernel.

```bash
-append "rootfstype=virtiofs root=myfs rw"
```

--------------------------------

### Configure QEMU kernel path

Source: https://virtio-fs.gitlab.io/howto-boot.html

Specifies the location of the guest kernel image for QEMU.

```bash
-kernel path/to/bzImage
```

--------------------------------

### Mount virtiofs with DAX in Guest

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Mount the virtiofs filesystem with the 'dax' option enabled in the guest. This requires kernel support and the corresponding QEMU device configuration.

```bash
mount -t virtiofs myfs /mnt -o dax
```

--------------------------------

### Mount virtiofs Filesystem in Guest

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Mount the virtiofs filesystem within the guest VM using the tag specified in the QEMU configuration. This makes the shared directory accessible.

```bash
mount -t virtiofs myfs /mnt
```

--------------------------------

### QEMU Configuration for virtiofs Socket

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Define a character device in QEMU to establish a socket connection with the virtiofsd daemon. The path must match the one used by virtiofsd.

```bash
-chardev socket,id=char0,path=/tmp/vhostqemu
```

--------------------------------

### QEMU Device Configuration for DAX

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Modify the vhost-user-fs-pci device configuration in QEMU to enable DAX (Direct Access) by specifying a cache size. This improves performance for certain workloads.

```bash
-device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs,cache-size=2G
```

--------------------------------

### Alternative Mount Syntax with DAX for Older Kernels (Pre-4.19)

Source: https://virtio-fs.gitlab.io/howto-qemu.html

This demonstrates the mount syntax for virtiofs with DAX enabled on Linux kernels older than 4.19. It includes the 'dax' option along with the older format for other parameters.

```bash
mount -t virtio_fs none /mnt -o tag=myfs,rootmode=040000,user_id=0,group_id=0,dax
```

--------------------------------

### QEMU Memory Sharing Configuration

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Configure QEMU to use memory sharing with virtiofsd by creating a memory backend file in /dev/shm. This is crucial for efficient data transfer.

```bash
-m 4G -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on -numa node,memdev=mem
```

--------------------------------

### Alternative Mount Syntax for Older Kernels (Pre-4.19)

Source: https://virtio-fs.gitlab.io/howto-qemu.html

This shows the mount syntax for virtiofs on Linux kernels older than 4.19, which required a different format for specifying options like tag, rootmode, user_id, and group_id.

```bash
mount -t virtio_fs none /mnt -o tag=myfs,rootmode=040000,user_id=0,group_id=0
```

--------------------------------

### Clone and Build virtiofsd

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Clone the virtiofsd repository and build the release version using Cargo. This daemon is essential for virtiofs functionality.

```bash
git clone https://gitlab.com/virtio-fs/virtiofsd.git
cd virtiofsd
cargo build --release
```

--------------------------------

### Configure Kernel for virtiofs

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Select the necessary configuration options for the Linux kernel to enable virtiofs support. CONFIG_VIRTIO_FS is required, and CONFIG_FUSE_DAX is optional.

```bash
CONFIG_VIRTIO_FS
CONFIG_FUSE_DAX   # optional
```

--------------------------------

### Clone Linux Kernel for virtiofs

Source: https://virtio-fs.gitlab.io/howto-qemu.html

Clone the Linux kernel repository to build a guest kernel with virtiofs support. Ensure your kernel version is 5.4 or later.

```bash
git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.