ChangeLog/4.0

System emulation

Incompatible changes

• The "handle" option to -fsdev and -virtfs has been removed. The "local" or "proxy" options should be used instead.

New deprecated options and features

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

Arm

• Allow AArch64 processors to boot from a kernel placed over 4GB into RAM
• arm: Implement the ARMv8.1-HPD extension
• arm: Implement the ARMv8.2-AA32HPD extension
• arm: Implement the ARMv8.1-LOR extension (as the trivial "no limited ordering regions provided" minimum)

s390

• vfio-ap now no longer inhibits usage of memory ballooners

Crypto subsystem

• The block storage encryption backends are now capable of using multiple threads for encryption/decryption

Monitor

• QMP can now execute a few commands "out of band". This is useful for postcopy recovery. For details, see docs/interop/qmp-spec.txt.
• query-qmp-schema reflects QEMU's build configuration more closely. For instance, stuff related to replication is properly absent when QEMU was built with --disable-replication.
• QMP events SHUTDOWN and RESET now carry a reason
• New QMP command query-current-machine
• QMP/HMP command system_wakeup now fails when the guest isn't suspended, or doesn't even support suspend.

TCG

• SoftFloat acceleration - where it is safe to do so the softfloat helpers will use the host FPU instructions yeilding significant performance increases

Build Information

Build Dependencies

• QEMU now requires at least GCC version 4.8 or Clang version 3.4 (or Clang from Xcode 5.1) to be built

Known issues

• see Planning/4.0