Simon Fairweather simon.n.fairweather at
Tue Apr 4 16:12:15 UTC 2023


In QEMU 8 virtiofsd has been removed in favor of the rust version. Which
includes options that are not longer supported,

Do you have a view on what should be used going forwards to support
virtiofsd in libvirt with qemu 8?

The options are showing as depreciated,
    -o <compat-options>...
            Options in a format compatible with the legacy implementation

Rust version options

virtiofsd backend 1.5.1
Launch a virtiofsd backend.

    virtiofsd [FLAGS] [OPTIONS] --fd <fd> --socket <socket> --socket-path

            Honor the O_DIRECT flag passed down by guest applications

            Tell the guest which directories are mount points

            Set log level to "debug" [deprecated]

            Compatibility option that has no effect [deprecated]

    -h, --help
            Prints help information

            Enable KILLPRIV V2 support

            Disable KILLPRIV V2 support [default]

            Disable support for READDIRPLUS operations

            Enable support for posix ACLs (implies --xattr)

            Print vhost-user.json backend program capabilities and exit

            Enable security label support. Expects SELinux xattr on file
creation from client and stores it in the newly
            created file
            Log to syslog [default: stderr]

    -V, --version
            Prints version information

            Enable writeback cache

            Enable support for extended attributes

        --cache <cache>
            The caching policy the file system should use (auto, always,
never) [default: auto]

    -o <compat-options>...
            Options in a format compatible with the legacy implementation

        --fd <fd>
            File descriptor for the listening socket

            When to use file handles to reference inodes instead of O_PATH
file descriptors (never, prefer, mandatory)

            - never: Never use file handles, always use O_PATH file

            - prefer: Attempt to generate file handles, but fall back to
O_PATH file descriptors where the underlying
            filesystem does not support file handles.  Useful when there
are various different filesystems under the
            shared directory and some of them do not support file handles.
 ("fallback" is a deprecated alias for

            - mandatory: Always use file handles, never fall back to O_PATH
file descriptors.

            Using file handles reduces the number of file descriptors
virtiofsd keeps open, which is not only helpful
            with resources, but may also be important in cases where
virtiofsd should only have file descriptors open
            for files that are open in the guest, e.g. to get around bad
interactions with NFS's silly renaming.
            [default: never]
        --log-level <log-level>
            Log level (error, warn, info, debug, trace, off) [default: info]

        --modcaps <modcaps>
            Modify the list of capabilities, e.g.,

        --rlimit-nofile <rlimit-nofile>
            Set maximum number of file descriptors (0 leaves rlimit
unchanged) [default: min(1000000,
        --sandbox <sandbox>
            Sandbox mechanism to isolate the daemon process (namespace,
chroot, none) [default: namespace]

        --seccomp <seccomp>
            Action to take when seccomp finds a not allowed syscall (none,
kill, log, trap) [default: kill]

        --shared-dir <shared-dir>
            Shared directory path

        --socket <socket>
            vhost-user socket path [deprecated]

        --socket-group <socket-group>
            Name of group for the vhost-user socket

        --socket-path <socket-path>
            vhost-user socket path

        --thread-pool-size <thread-pool-size>
            Maximum thread pool size. A value of "0" disables the pool
[default: 0]

        --xattrmap <xattrmap>
            Add custom rules for translating extended attributes between
host and guest (e.g. :map::user.virtiofs.:)

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