QEMU 2.4.1 发布,开源模拟器

来源: 投稿
作者: 如比如比
2015-11-06 00:00:00

QEMU 2.4.1 发布,此版本主要改进:


  • The handling of the floppy device controller is different between <2.4 and >=2.4 machine types that use the Q35 chipset (e.g. "-M pc-q35-2.3" vs. "-M pc-q35-2.4").  This can cause problems if you are defining floppy drives with command-line options such as "-global isa-fdc.driveA=id.

  • The ARM 'virt' board default interface type has changed from IDE to virtio. This means that some incorrect command lines that we previously silently accepted will now fail with an error message like "qemu-system-arm: -drive file=img.qcow2,id=foo: Drive 'foo' is already in use because it has been automatically connected to another device (did you need 'if=none' in the drive options?)". As the error message suggests, you should add "if=none" to the -drive option to fix this.


  • Major fixes to the implementation of floating point exceptions.


  • New board model xlnx-ep108

  • Support for ACPI v5.1 tables in the "-M virt" board.

  • Support for instantiation sysbus devices from the command line (using "-device") in the "-M virt" board.

  • Emulation of the stream ID for MSI writes, for use in GICv3.

  • The "virt" board default drive type is now virtio; this means that drives created with if=virtio or with no if= specification will be created as drives plugged into a virtio-blk-pci device. Short form options like -hda will also create this kind of drive. (Note that at time of writing Linux only supports the virt board's PCI controller for 32-bit ARM kernels; support has not yet made it into the 64-bit kernels. So 64-bit guests will need to continue using long command lines and virtio-mmio for now.) Unfortunately this means that some old command lines will need to change -- see the "incompatible changes" section above for details.


  • More accurate emulation of the dp8393x network card and RC4030 DMA/IOMMU controller.

  • Support for microMIPS32 R6 emulation (enabled in new "-cpu mips32r6-generic")

  • Support for unaligned R6 and MSA memory accesses in TCG

  • Support for XPA in MIPS32 and LPA in MIPS64 (eXtended and Large Physical Addressing) emulation

  • Support for MIPS UHI semihosting


  • The default RAM size for the pseries machine is 512 MB.

  • Support of PCI device hotplug on SPAPR (pSeries).


  • Channel I/O is now available when running with TCG.  Thus, the default machine for qemu-system-s390x is now s390-ccw.

  • Several other fixes for TCG (emulation) mode.

  • Extended name and UUID in STSI 3.2.2 information block

  • Support for reading/writing guest memory while holding the IPTE lock under KVM, including access register mode

  • Various cleanups in the s390-virtio and virtio-ccw transports

  • Support for diag288 watchdog (KVM only).

  • Support for vector registers

  • Add virtio-1 specific ccws to virtio-ccw (SET_REV and v1 version of SET_VQ)

    • Revision 1 (and therefore virtio 1) is not yet enabled, however.

  • The s390-ccw-virtio machine is now versioned; the first versioned machine is s390-ccw-virtio-2.4

    • The s390-ccw alias has been removed


  • Optimizations to code generated by TCG.


  • Fix SunOS 4.1.4 boot on sun4m with OpenBIOS


  • Improvements to system management mode emulation, including support for high SMRAM and TSEG on machines using the Q35 chipset.

  • q35 machine types starting with pc-q35-2.4.0 do not have a floppy disk controller.  It will be created if you use "-drive if=floppy", "-fda" or "-fdb" to add a floppy disk drive, or it can be created if necessary with "-device isa-fdc".

  • q35 now implements the TCO watchdog.  Unlike real hardware, the watchdog is disabled when the virtual machine boot, so as to let existing firmware run with new QEMU.  This may change in the future, but the change would be restricted to new machine types.


  • Support for MMIO operations outside the "big QEMU lock".  For now, this only applies to the ACPI PM timer, which can alone improve performance substantially for very large Windows guests as long as they do not span multiple NUMA nodes in the host.  For guests that span multiple NUMA nodes more kernel changes are required.

  • Support for system management mode (requires Linux 4.1).

  • When running under KVM, CPUID information includes the ARAT ("Always running APIC timer") bit

详细更新内容请参照 Download 。


QEMU是一套由Fabrice Bellard所编写的模拟处理器的自由软件。它与Bochs,PearPC近似,但其具有某些后两者所不具备的特性,如高速度及跨平台的特性。经由kqemu这个开源的加速器,QEMU能模拟至接近真实电脑的速度。QEMU有两种主要运作模倾:

  • User mode模拟模式,亦即是使用者模式。QEMU 能启动那些为不同中央处理器编译的Linux程序。而Wine及 Dosemu是其主要目标。

  • System mode模拟模式,亦即是系统模式。QEMU能模拟整个电脑系统,包括中央处理器及其他周边设备。它使得为系统源代码进行测试及除错工作变得容易。其亦能用来在一部主机上虚拟数部不同虚拟电脑。

QEMU的主体部份是在LGPL下发布的,而其系统模式模拟与kqemu加速器则是在GPL下发布。使用kqemu可使QEMU能模拟至接近实机速度,但其在虚拟的操作系统是Microsoft Windows 98或以下的情况下是无用的。


  • 可以模拟 IA-32 (x86)个人电脑,AMD64个人电脑, MIPS R4000, 升阳的 SPARC sun3 与 PowerPC (PReP 及 Power Macintosh)架构

  • 支持其他架构,不论在主机或虚拟系统上(请参看QEMU主页以获取完整的清单)

  • 增加了模拟速度,某些程式甚至可以实时运行

  • 可以在其他平台上运行Linux的程式

  • 可以储存及还原运行状态(如运行中的程式)

  • 可以虚拟网络卡

  • 可模拟多CPU

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