On Mon, Nov 17, 2025 at 05:55:46PM +0000, Nikita Kalyazin wrote: > In our use case, Firecracker snapshot-restore using UFFD [1], we will use > UFFD minor/continue to respond to guest_memfd faults in user mappings > primarily due to VMM accesses that are required for PV (virtio) device > emulation and also KVM accesses when decoding MMIO operations on x86.
I'm curious if firecracker plans to support live snapshot save. When with something like ioctls_supported flags, guest-memfd can declare support for wr-protect support easily too, and synchronous userfaultfd wr-protect traps will be an efficient way to do live save. I'm guessing it's not an immediate demand now or it would have been asked already supporting both MINOR and WP, but I just want to raise this question. Qemu already supports live snapshot save, so it'll always be good gmem can also support wp at some point, but it can be done later too. Thanks, -- Peter Xu
