pkernfs: Persisting guest memory and kernel/device state safely...
summary
Proposal to preserve guest RAM and kernel/device state across kexec by storing page tables and driver blobs in a new in‑memory persistent filesystem: pkernfs. Uses reserved DRAM to keep guest pages out of the direct map, avoid struct page overhead and allow DMA/IOMMU to continue using IOMMU page tables through kexec. Works with QEMU live‑update patches for PCI passthrough; demo shows PCI device assignment surviving kexec. Metadata sizes reported as tens of megabytes, not hundreds.
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chapters (26)
- 0:00Introduction to live updates
- 1:08Current live update capabilities
- 2:11Challenges with device pass-through
- 3:54Use cases for kernel state persistence
- 4:59Proposed solutions overview
- 6:21Composability of solutions
- 7:47Complexity of persistent memory
- 9:13Device Tree and metadata
- 11:44Global vs VM-specific data
- 13:08ABI vs optimization for state
- 15:34Channel and data format
- 17:00Integrity measurements across kernels
- 19:25Hibernation vs live update
- 21:11Device shutdown callbacks
- 24:44Emulated persistent memory
- 27:35Device Tree handover proposal
- 28:40Serialization and protocol tasks
- 31:31KVM replay state and fragmentation
- 32:56Fundamental base layers
- 34:01User space vs kernel state
- 35:46Live update in EC2
- 37:11PE FS and additional use cases
- 39:18PE FS as a base primitive
- 40:03Language-theoretic security
- 41:35Measurement and trust boundaries
- 42:17F Trace handover proposal
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