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.
- The "-virtioconsole" option has been removed. Use "-device virtconsole" instead.
- The "-no-frame" option has been removed. It was only usable with SDL1.2, and support for this library has been suspended now.
- The "-enable-hax" option has been removed. Use "-accel hax" instead.
- The legacy "ivshmem" device has been removed. Use "ivshmem-doorbell" or "ivshmem-plain" instead.
- The x86 machine types "pc-0.10" and "pc-0.11" have been removed. Use a newer machine type instead.
- The "irq" property of the "spapr-vscsi", "spapr-vlan" and "spapr-vty" devices has been removed with no replacement.
New deprecated options and features
cpu-add
QMP/HMP command- machine-types
pc-0.12
,pc-0.13
,pc-0.14
andpc-0.15
qemu-nbd --partition=N
option
Consult the "Deprecated Features" appendix for the full list of historically deprecated features/options.
Alpha
Arm
- Implement the ARMv8.0-SB extension
- Implement the ARMv8.0-PredInv extension
- Implement the ARMv8.1-HPD extension
- Implement the ARMv8.1-LOR extension (as the trivial "no limited ordering regions provided" minimum)
- Implement the ARMv8.2-FHM extension
- Implement the ARMv8.2-AA32HPD extension
- Implement the ARMv8.3-PAuth extension
- Implement the ARMv8.3-JSConv extension
- Implement the ARMv8.4-CondM extension
- Implement the ARMv8.5-CondM extension
- Implement the ARMv8.5-FRINT extension
- Implement the Armv8.5-BTI extension for system emulation mode
- New machines "musca-a" and "musca-b1" -- these model the Arm "Musca" development boards
- New machine "mps2-an521" -- this is a model of the AN521 FPGA image for the MPS2 devboard
- Support TBI (top-byte-ignore) properly for linux-user mode
- The micro:bit board now boots simple MicroPython programs since device emulation for the timer, GPIO, NVMC and RNG has been added
- The cubieboard model now implements the 'A' SRAM
- AArch64 processors can now boot from a kernel placed over 4GB into RAM
- The stellaris boards ("lm3s6965evb", "lm3s811evb") now implement the watchdog timer device
- The BLK_MAX register in the TZ MPC device now reports the correct value
- The u-boot "noload" image type is now supported for the Arm virt board
- The Arm virt board now permits more than 255GB of RAM
- stm32f2xx_usart: Do not update data register when device is disabled
- virt board ACPI tables: COHACC override flag now correctly set in IORT SMMUv3 node
- AArch32 exception return is fixed to permit a switch from Mon->Hyp mode
- ftgmac100: implement the new MDIO interface on Aspeed SoC
- Emulation of the ARM PMU has been improved
- Fix various places where we failed to UNDEF invalid A64 instructions
- Don't UNDEF a valid FCMLA on 32-bit inputs
- Make FPSCR/FPCR trapped-exception bits RAZ/WI
- Fixed a bug in handling clearing of FPSCR/FPSR exception status bits
- armv7m_nvic: Allow byte accesses to SHPR1 register
- linux-user: support HWCAP_CPUID which exposes ID registers to user code
- Fixed a bug where the v8M MPU was always using the background region if it was enabled, rather than only if there was no hit on a more specific region
HPPA
- Fix condition code generation for "add,<" & "add,<=".
- Fix the output for "dcor".
- Fix pci config address access.
- Map CPU HPA regions into PCI address space.
M68k
- The "mcf5208evb" machine now supports loading of firmware binaries with the "-bios" option.
Microblaze
MIPS
- Added support for I7200 CPU (nanoMIPS32 ISA + DSP ASE; system mode only).
- Added support for I6500 CPU (MIPS64R6 ISA + MSA ASE + multicore features).
- Added support for QMP-based querying of the available CPU types.
- Added support for SAARI and SAAR configuration registers.
- Added support for MTTCG (multi-threaded TCG).
- Improved support for ITU (Interthread Communication Unit).
- Improved support for Fulong 2E machine.
- Improved end user documentation.
- Fixed build for MIPS n32 hosts.
Nios2
OpenRISC
PowerPC
- sam460ex can now have 2GB memory
- pseries default CPU type is now POWER9
- pseries now supports the XIVE interrupt controller of POWER9 (emulated version only)
- pseries can now select its interrupt controller through a new ic-mode machine option
- pseries can now control the exposure of the host model and system-id through the new host-model and host-serial machine options
- pseries now supports "-vga cirrus"
- pseries now supports hot plug and unplug of PCI Host Bridges (PHBs)
- powernv now supports POWER9 hash and radix MMU modes
- powernv now allows kernel images up to 256MiB
- gdbstub can now access SPRs
- mac99 machine now defaults to sungem NIC instead of ne2k_pci
RISC-V
- The virt board now supports PCI and USB.
- The FS field of mstatus now supports three states (dirty, clean, and off).
- The TSR, TW, and TVM fields of mstatus are now implemented.
- The misa CSR is now writable.
s390
CPU models
- The 'zpci' feature bit is now indicated by default in the 'qemu' cpu model.
- The z14 cpu model now includes the multiple epoch and PTFF enhancement features per default.
- A cpu model for the z14 GA 2 has been added.
Devices
- vfio-ap now no longer inhibits usage of memory ballooners.
- zPCI devices now provide some instruction counters to the guest (for a Linux guest, check /sys/kernel/debug/pci/<function>/statistics).
- zPCI devices are now explicitly marked as unmigratable. No change in functionality, migration support for zPCI devices had never been implemented.
- vfio-ap now supports hot(un)plug of the vfio-ap device.
TCG
- Support for the floating-point extension facility has been added.
SH
SPARC
- Fix Solaris boot on SS-10/SS-20 machines with OpenBIOS (OpenBIOS)
TileGX
Tricore
- Fixed mixed up operands in CADDN and CADD
x86
- The HAX accelerator is now supported for POSIX hosts other than Darwin, including Linux and NetBSD.
Xtensa
- xtfpga boards provide SMP support expected by linux (interrupt distributor, IPI and runstall)
- New test_mmuhifi_c3 core configuration capable of running SMP linux
- Flexible length instructions extension (FLIX) is now supported
Device emulation and assignment
ACPI
Audio
Block devices
- IDE/via: Implement PCI IDE mode
- virtio-blk: DISCARD and WRITE_ZEROES support
Graphics
Input devices
I2C
- smbus_eeprom: Will now transfer its state
- pm_smbus: I2C block transfers will now work properly
- pm_smbus: state transfer will now work properly
IPMI
Network devices
- pvrdma: Add support for RDMA MAD
- pvrdma: Removed the dev-caps-max-sge parameter
NVDIMM
PCI/PCIe
SCSI
SMBIOS
TPM
- ACPI HID for TPM TIS for TPM 2.0 has been corrected to MSFT0101; this should allow all Operating Systems to use the TPM 2.0 through the TIS interface
- QEMU support for TPM PPI (Physical Presence Interface) allows OS to use PPI functionality if the firmware supports it
USB
VFIO
virtio
Xen
fw_cfg
9pfs
Audio
Character devices
- The "wait" option for the socket backend is now forbidden for client sockets. It previously had no functional effect except for server sockets.
- The "reconnect" option for the socket backend is now forbidden for server sockets. It previously had no functional effect except for client sockets.
Crypto subsystem
- The block storage encryption backends are now capable of using multiple threads for encryption/decryption
GUI
- Add
-display spice-app
: configure & launch a Spice client. With upcoming virt-viewer 8.0, this will present a UI similar to QEMU GTK (with monitor & console etc), but running in a separate process. - Support for building against SDL1.2 has been deleted. SDL2 should be used instead.
- The VNC server will no longer accidentally delete its UNIX listener socket when clients disconnect
Host support
Memory backends
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
, and stuff specific to other targets is properly absent.- 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. - QMP/HMP command
cpu-add
is now deprecated - New QMP commands
block-dirty-bitmap-enable
,block-dirty-bitmap-disable
, andblock-dirty-bitmap-merge
, plus enhancements totransaction
,nbd-server-add
,query-block
, andblock-dirty-bitmap-add
, allow a management application to perform incremental backups with an NBD client as a consumer learning which portions of the disk were changed while the bitmap was enabled. The experimental commandsx-block-dirty-bitmap-enable
,x-block-dirty-bitmap-disable
,x-block-dirty-bitmap-merge
andx-nbd-server-add-bitmap
were removed in favor of the stable commands.
Migration
- free page hinting through virtio-balloon to avoid migrating unused pages
- ignore-shared feature for skipping shared memory blocks for migration-on-same-host hacks
Network
- new QMP/HMP command
announce_self
to trigger generation of broadcast RARP frames to update network switches.
Block devices and tools
- Improved tracing and error diagnostics for NBD code
- Fix infinite loop in DMG image format
- A new
qemu-nbd --bitmap
option allows the exposure of a persistent dirty bitmap for a qcow2 image not in use by a guest, in a simpler manner than the older procedure of using QMP commands to a temporary qemu process attached to the file. - A new
qemu-nbd --list
option enables the ability to probe a remote NBD server for information about what it is exporting. - The
qemu-nbd --partition=N
option has been deprecated; it does not support GPT partitions, and has always been broken for MBR logical partition 6 and beyond. Its functionality of exporting a subset of the guest-visible data can still be accomplished with--image-opts driver=raw,offset=X,size=Y
. qemu-img info
now displays information about persistent bitmaps stored in qcow2 files.- The size of qcow2 cache entries is reduced by default to make better use of the memory and increase the I/O performance.
Tracing
- The new qemu-trace-stap script makes it convenient to collect traces without writing SystemTap scripts. See "man qemu-trace-stap" for details.
Miscellaneous
- QEMU's builtin gdbstub now supports the gdb multiprocess extension. Boards which have more than one cluster of CPUs (like the 'xlnx-zcu102' board when run with '-smp 6') will report them as being two processes (each of which has one thread per CPU in the cluster). You will need at least GDB 7.2. Attach to QEMU with a GDB command sequence like:
target extended :1234
add-inferior
inferior 2
attach 2
- and then the "info threads" command should show 2 processes.
- QEMU will default to KVM when compiled with --disable-tcg or when launched from an executable whose name ends with "kvm".
- Common Python code now lives under "python", instead of under "scripts". That directory now contains a proper "qemu" Python module. qmp Python libraries, previously under "scripts/qmp" have also moved to the same location.
User-mode emulation
- The docker.py script now checks the path and persistence status of binfmt_misc entries when installing and updating user-mode docker containers
TCG
- SoftFloat acceleration - where it is safe to do so, the softfloat helpers will use host floating-point instructions yielding significant performance increases
- Dynamic sizing of software TLBs, yielding noticable performance increases
- Host support for 64-bit RISC-V.
Guest agent
Build Information
CI
- FreeBSD builds are now done via https://cirrus-ci.com/github/qemu/qemu
- Additional CI builds are now run if you host your repo on gitlab
GIT submodules
Build Dependencies
- QEMU now requires at least GCC version 4.8 or Clang version 3.4 (equivalent to Clang from Xcode 5.1 on macOS) to be built
- Running the QEMU testsuite now requires the Perl Test::Harness module. Most Linux and BSD distributions however install it by default together with Perl.
- For OSX hosts, our minimum supported version is now OSX 10.10. We have fixed the bug which meant that some guests would crash when running with the Cocoa UI on OSX 10.14 Mojave.
- We now have some documentation in rST format which we process with Sphinx. The host system must now have the 'build-sphinx' program available (version 1.3 or better) in order for any of the documentation to be built.
Known issues
- see Planning/4.0