project release . As an emulator, QEMU allows the execution of programs compiled for one hardware platform on a system with a completely different architecture, for example, running an ARM application on an x86-compatible PC. In virtualization mode, QEMU's code execution performance in an isolated environment is close to that of a native system due to direct instruction execution on the CPU and the involvement of the Xen hypervisor or KVM module.
The project was initially created by Fabrice Bellard to enable the execution of Linux executable files compiled for the x86 platform on architectures different from x86. Over the years of development, support was added for full emulation of 14 hardware architectures, and the number of emulated hardware devices exceeded 400. More than 2200 changes from 198 developers were made in preparation for version 4.2.
Key , added in QEMU 4.2:
- The classic TCG (Tiny Code Generator) now supports plugins for monitoring processor instructions and memory addresses;
- In the block device driver (Network Block Device), more efficient handling of copy requests during read (copy-on-read) has been implemented. The NBD server code has been optimized for copying sparse images (with gaps). General improvements have been made to the NBD client and server implementation;
- The performance of LUKS disk encryption has been improved using the AES-XTS algorithm;
- Support for the 'failover_pair_id' property has been added in vfio-pci to simplify the migration of VFIO devices;
- Support for the virtio-compatible 2 standard and the packed virtual queues mechanism defined in the virtio 1.1 specification has been added in virtio-mmio () for data exchange with virtual I/O devices in batch mode;
- The x86 architecture emulator has introduced a new type of emulated machines called 'microvm', which use virtio-mmio instead of PCI for performance optimization. The ability to enable and disable VMX via the '-cpu' flags has been implemented. Support for emulation of AVX512 BFloat16 extensions has been added. New CPU models Denverton (server SoC based on Atom), Snowridge, and Dhyana are now supported. Support for the macOS Hypervisor Framework ('-accel hvf') has been stabilized;
- The ARM architecture emulator has added support for emulating the Aspeed AST2600 SoC ('ast2600-evb'). Support for Semihosting 2.0 technology with STDOUT_STDERR/EXIT_EXTENDED extensions has been added, allowing the emulated device to use stdout, stderr, and stdin for file creation on the host side. In KVM, the ability to use more than 256 CPUs has been introduced, along with support for SVE SIMD instructions. In virtual machines of type '', support for hot plug memory has been implemented. The performance of emulation using the TCG code generator has been increased.
- The PowerPC architecture emulator now supports the emulation of POWER9 instructions mffsce, mffscrn, and mffscrni. Support for the system devices Homer and OCC SRAM has been added in the emulated "powernv" machines;
- The RISC-V architecture emulator has added the "-initrd" option and the ability to view the complete state of the architecture in the debugger;
- The s390 architecture emulator now supports IEP (Instruction Execution Protection) instructions;
- The 68k architecture emulator has introduced initial support for emulating the Macintosh Quadro 800 and classic NeXTcube systems;
- The xtensa architecture emulator has added a new type of emulated machine "virt" and implemented support for the ABI call0 for user-space emulation.
Source: opennet.ru
