ChangeLog/10.1

Release schedule: Planning/10.1.

System emulation

Removed features and incompatible changes

Consult the 'Removed features' page for details of suggested replacement functionality.

New deprecated options and features

Consult the "Deprecated Features" chapter of the QEMU System Emulation User's Guide for further details of the deprecations and their suggested replacements.

RISC-V

ISA and Extensions

• Use tail pseudoinstruction for calling tail
• Fix some RISC-V vector instruction corner cases

Machines

• Add support for RIMT to virt machine ACPI
• Improve Microchip Polarfire SoC customization

Fixes and Misc

• Don't allow PMP RLB to bypass rule privileges
• Fix checks on writes to pmpcfg in Smepmp MML mode
• Generate strided vector loads/stores with tcg nodes
• Fix endless translation loop on big endian systems
• Fix write_misa vs aligned next_pc
• KVM CSR fixes

Device emulation and assignment

9pfs

• Fixes for file descriptor reclaiming algorithm (i.e. when running towards host's allowed limit of max. open file descriptors).

• Additional fixes on use-after-unlink idiom (i.e. client operations on a file descriptor after file has been removed).

Migration

• RDMA live migration starts to support ipv6
• Postcopy preempt mode optimization on sequential memory accesses (e.g. video streaming)
• Initial supports of enabling both multifd and postcopy features (multifd is only enabled during precopy so far)
• Fix VFIO multifd live migration when tcp zerocopy send is enabled

Monitor

QMP

• blockdev-mirror gained a new boolean flag target-is-zero that can be used to optimize mirroring of a sparse file to a destination that already reads as zero. Even without use of this flag, mirroring has been optimized to do less work on portions of the source that read as zero.

Build Information

Rust usage

The minimum supported version of Rust is now 1.77.

• On Debian bookworm, it is available in the rustc-web package except for the mips64el architecture; Rust support for mips64el requires Debian trixie or newer.
• On Ubuntu 22.04 and 24.04, it is available in the rust-1.77 package; the RUSTC and RUSTDOC environment variables must point to /usr/bin/rustc-1.77 and /usr/bin/rustdoc-1.77 respectively.

Debian bookworm remains a supported platform for QEMU; support for Rust is still considered experimental and not stable, and it is not recommended to be used for anything other than development.

Host support

• Support for Debian bullseye has been dropped.
• Ninja 1.9 is now required. This version of Ninja was already found on all supported platforms (including Debian bullseye) as of QEMU 10.0.

Known issues

• See https://gitlab.com/qemu-project/qemu/-/milestones/16