QEMU AI policy and PostgreSQL correctness fixes

QEMU and PostgreSQL development led the day, with a revised AI contribution policy and multiple correctness and performance threads under review. Virtualization work also advanced on ARM64 accelerators, multi-target binaries, and named CPU models for migration.

QEMU revises AI contribution policy

QEMU developers posted a fourth revision of a proposed policy on AI-generated contributions, relaxing an earlier blanket ban. The draft adds attestation trailers and requires pre-approval for large contributions. The shift gives maintainers a traceable path for automated assistance while keeping review standards intact.

PostgreSQL 19 NOT NULL simplification bugs

Hackers reported multiple correctness bugs in PostgreSQL 19 expression simplification for NOT NULL predicates. The faults affect ON CONFLICT and MERGE paths, with fixes posted and open items still under discussion. Reliable conflict and merge behavior matters for applications targeting the next major release.

ARM64 support for QEMU MSHV accelerator

A sixth patch series adds ARM64 guest support to QEMU's MSHV accelerator. It refactors the existing x86 path and introduces a new ARM backend for vCPU, MMIO, and vGIC handling. The work broadens hypervisor choices for ARM64 guests on the MSHV stack.

Multi-target qemu-system binary refactor

Patches rework machine type registration and selection so a single qemu-system binary can cover multiple targets without name collisions. One change avoids calling target_info() from virtio-mem class_init. The series aims to simplify packaging and reduce binary proliferation across architectures.

Partition attach cost grows with pg_constraint

Attaching partitions in PostgreSQL 18 slows linearly because CloneFkReferenced sequentially scans pg_constraint after not-null constraints were moved into that catalog. A proposed patch adds an index on confrelid to cut the cost. Large partitioned deployments see attach latency rise until the scan is addressed.

Conflict log history for logical replication

PostgreSQL hackers continue active review of patches that add a conflict log history table for logical replication. The long thread iterates on design and implementation details. Persistent conflict records would aid diagnosis and recovery in multi-node replication setups.

Slot invalidations persist before publish

A patch ensures replication slot invalidations are written to disk before shared-memory state is published. Publishing first can leave restarts with inconsistent slot views. The ordering fix hardens logical and physical replication against that class of restart failure.

Named Arm64 CPU models for KVM

An RFC fourth version proposes hierarchical named CPU models for Arm64 on KVM, along with QMP introspection. The goal is safer live migration across heterogeneous hosts. Named models would make compatibility checks more predictable for Arm64 fleets.