Module rootfs 

Guest rootfs management module.

This module handles preparation and management of guest rootfs for MicroVM instances. The rootfs contains the minimal filesystem required to boot the guest agent.

Two rootfs providers are available:

• CopyProvider — full recursive copy (works everywhere)
• OverlayProvider — Linux overlayfs mount (near-instant CoW)

Structs

AttachedRootfs

A temporarily attached persistent rootfs.

CopyProvider

Full recursive copy provider — works on all platforms.

GuestLayout

Guest filesystem layout.

OverlayProvider

Overlayfs provider — near-instant CoW mounts (Linux only).

RootfsBuilder

Builder for creating guest rootfs.

RootfsFileInfo

Minimal file metadata needed to classify filesystem changes.

Constants

DIFF_BASELINE_FILE

Filename stored beside each box rootfs.

GUEST_WORKDIR

Working directory inside the guest VM.

Traits

RootfsProvider

Abstracts how a rootfs directory is prepared for a box from a cached lower layer.

Functions

attach_persistent_rootfs

Attach an existing platform-backed persistent rootfs for offline access.

create_diff_baseline_if_absent

Persist the first pristine baseline for a box without ever replacing it.

default_provider

Auto-detect the best available rootfs provider for the current platform.

read_persisted_exit_code

Read the exit code persisted by guest-init from the active writable rootfs.

stage_box_terminal_rootfs_metadata

Invalidate the last clean-shutdown metadata generation before launching a box, retaining it at the one-shot replay path used by guest-init.

unmount_box_overlay

Unmount a box’s overlayfs merged view — best-effort and idempotent.

unmount_box_rootfs

Unmount a platform-specific writable rootfs mount.

walk_rootfs

Capture a rootfs tree while excluding runtime-owned control files.