Encore Booted Identical OCI Images on Firecracker and Apple's Virtualization.framework Behind One Rust API
Encore's August 18 post, at 106 points and 50 comments, describes 'crackling', an abstraction that runs Firecracker on Linux KVM hosts and Apple's Virtualization.framework on macOS while booting the same OCI images on both. Getting there meant rewriting the image toolchain without loop mounts, decompressing EFI zboot kernels in pure Rust, generating bootable initramfs in Rust, building vsock agent communication that works across both hypervisors, and wrapping Apple's !Send + !Sync framework objects in dispatch queues inside a tokio runtime. No boot-time or overhead numbers are published, which is the gap. Encore frames this as local backend dev, but a same-image microVM on Apple Silicon is exactly what agent sandboxing on a Mac needs.
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