ChangeLog/5.0

System emulation

Incompatible changes

• The bluetooth code has been removed without replacement. It was quite neglected over the years and likely not usable anymore. You can passthrough a dedicated USB bluetooth dongle to guests on most machines instead if you still need bluetooth in your guest.
• The -virtfs_synth option has been removed. You can use -fsdev synth together with -device virtio-9p-... instead.
• The pc-0.12, pc-0.13, pc-0.14, pc-0.15 machines have been removed.
• The "-accel" and "-machine accel=" options are now incompatible with each other.
• The "-tb-size N" option has been replaced by "-accel tcg,tb-size=N".

New deprecated options and features

Consult the "Deprecated Features" appendix for the full list of historically deprecated features/options.

Arm

• The Cortex-M7 CPU is now supported
• New board: tacoma-bmc
• QEMU now correctly implements trapping of more EL1 system register accesses to EL2 (eg HCR_EL2 TID1, TID2 bits, HSTR_EL2)
• The no-op system registers required for a "trivial Jazelle" implementation have been added
• The DC CVAP and DC CVADP instructions are now supported
• Support for blocking semiconsole SYS_READC

PowerPC

• pseries machine type
  • No longer require a reconfiguration reboot for a guest selecting XIVE interrupt controller when ic-mode=dual
  • Now consumes less host resources when running a KVM guest with XIVE (with a recent enough host kernel). This allows running more concurrent guests with KVM accelerated XIVE.
• powernv machine type
  • Numerous improvements to the model
  • Can now run KVM guests under a TCG emulated powernv machine
  • Basic POWER10 support

Migration

• Add dbus-vmstate, a backend that allows external processes to migrate their data along with QEMU. See the documentation.

Tracing

• DEBUG_MMAP build hack replaced by target_mmap_* tracepoints

Miscellaneous

• It is now possible to specify multiple "-accel" options. The first available accelerator will be used. For example, "-machine accel=kvm:tcg" can now be expressed as "-accel kvm -accel tcg" with the added possibility of including options to configure the accelerator.
• KVM and Xen-specific machine options have been moved to "-accel"; the previous way to set the option is still available for backwards-compatibility. The options that were moved are:
  • "-machine kernel_irqchip=" (now "-accel kvm,kernel-irqchip=")
  • "-machine kvm_shadow_mem=" (now "-accel kvm,kvm-shadow-mem=")
  • "-machine igd-passthru=" (now "-accel xen,igd-passthrough=")
• changing the logfile via HMP is now atomically thread-safe

Guest agent

• The 'set-guest-time' command is now fenced off on systems that do not have the 'hwclock' command available (e.g. on s390x).

Build Information

Container Based Builds

• --disable-containers allows configure to skip attempting to use them from cross builds (useful on non-x86 builds)

Testing

• multiarch targets added to Travis

Known issues

• see Planning/5.0