Qemu 0.14.1 released!

I just found out that a new version of Qemu has hit the street!  From the changelog:

  • Version 0.14.1 (commit)
  • virtio-blk: fail unaligned requests (commit)
  • qed: Fix consistency check on 32-bit hosts (commit)
  • exit if -drive specified is invalid instead of ignoring the “wrong” -drive (commit)
  • vhost: fix dirty page handling (commit)
  • Do not delete BlockDriverState when deleting the drive (commit)
  • vnc: tight: Fix crash after 2GB of output (commit)
  • lan9118: Ignore write to MAC_VLAN1 register (commit)
  • Don’t allow multiwrites against a block device without underlying medium (commit)
  • lsi53c895a: add support for ABORT messages (commit)
  • virtio-pci: fix bus master work around on load (commit)
  • fix applesmc REV key (commit)
  • rbd: don’t link with -lcrypto (commit)
  • net: Add the missing option declaration of “vhostforce” (commit)
  • lsi53c895a: Update dnad when skipping MSGOUT bytes (commit)
  • Revert “prep: Disable second IDE channel, as long as ISA IDE emulation doesn’t support same irq for both channels” (commit)
  • isa-bus: Remove bogus IRQ sharing check (commit)
  • virtio-net: Fix lduw_p() pointer argument of wrong size (commit)
  • hw/sd.c: Add missing state change for SD_STATUS, SEND_NUM_WR_BLOCKS (commit)
  • vnc: Fix fatal crash with vnc reverse mode (commit)
  • qemu-char: Check for missing backend name (commit)

I’ve also included my patches to enable ctrl+alt+d for a quick control alt delete, ctrl+alt+r for reset, and the ISA Cirrus adapter.

As always, I’ll have win32 builds up in the usual spot.  i386/x86_64 and everything else.  I’ve tested these on Windows 7 x86_64, and they should work on XP & Vista i386 as well.

Also I’ve switched this to 7zip to save space.


This entry was posted in qemu, random updates, virtualization and tagged by neozeed. Bookmark the permalink.

About neozeed

What is there to tell? I’ve loved UNIX like things since I was first exposed to QNX in highschool (we had the Unisys ICONS!), and spent the better time of my teenage years trying to get my own UNIX… I should have bought Coherent in retrospect.. Anyways latched onto Linux in 1992, and then got some old BSD admin books and have been hooked on the VAX BSD & other big/ancient things since…!

11 thoughts on “Qemu 0.14.1 released!

  1. It was a lot easier to setup than I had anticipated… Then again the last time I looked at doing this it was 2007… I’m sure things have gotten a lot better since then!

    And thanks!

  2. Qemu operates at low speed with a virtual hard disk. I tried to format raw, qcow, vdi. On Windows XP 32-bit everything is fine. But for Windows 7 64-bit is such a problem. MS-DOS 6.22 is installed in Qemu on Windows 7, a few minutes, but on XP for a few seconds. Tried Qemu 0.14.0, 0.14.1, 0.15.0. Why such a low speed? 🙁 In Safe Mode, Windows 7 is still a problem, too. How to solve this problem on Windows 7? Can you help? Thanks in advance.
    Sorry for my English.

    • I’ve never benchmarked the speed of the disks… I know that expanding/growing a qcow/qcow2/vmdk/vpc image can be quite painful, however if RAW is slow as well… That’d be quite bad.

      How much memory do you have?

      • memory 4 GB
        I run Qemu with
        qemu.exe -M pc -L pc-bios -m 16 -boot menu=on -hda disk1.disk -fda DOS1.IMG

      • On raw format writing speed – few KiloBytes per seconds. 4-10 Kb/sec 🙁
        On XP works fine. Why?

      • I have no idea… here is a small test I just ran with Qemu 0.15.0 …

        # time dd if=/dev/zero of=bla bs=1000000 count=50
        50+0 records in
        50+0 records out
        50000000 bytes transferred in 48.727 secs (1026116 bytes/sec)
        0m48.76s real 0m0.00s user 0m9.64s system

  3. Yes! 🙂 Problem solved! The problem was related to the write caching on the hard drive. Caching in Qemu depends on the parameter “-cache cacheparameter” in “-drive”. This option is described in detail in the documentation. cacheparameter is “none”, “writeback”, “unsafe”, or “writethrough”. “directsync” is in the documentation, but I have not worked. With and without caching – different speed of the disc.
    I tested the write speed to virtual hard disk.
    Checked the speed install MS-DOS 6.22 in Qemu 0.14.1 and 0.15.0.
    fast – copying files takes 1 – 2 seconds with a single floppy.
    slow – copying files takes longer than 20 seconds (maybe even more than one minute) with a single floppy.
    Columns – parameters of cache.
    Rows – virtual hard disk formats.
    Host OS – Windows 7 64-bit
    Qemu 0.14.1 =>
    | raw | slow | fast | fast |slow |
    | qcow | slow | slow* | fast | slow|
    | qcow2 | slow | fast | fast | slow|
    | vdi | slow | fast | fast | slow|
    Qemu 0.15.0 =>
    | raw | slow | fast | fast |fast |
    | qcow | slow | slow* | fast | slow|
    | qcow2 | slow | fast | fast | fast|
    | vdi | slow | fast | fast | fast|
    * – Why slow? I don’t know. 🙁
    Interesting test results.
    “writethrough” option is the default. The result was a low speed of write to the virtual hard disk.
    I replaced “-hda disk1.qcow2” to
    “-drive file=disk1.qcow2,if=ide,index=0,media=disk,cache=writeback”
    And it works fast.

    • Wow that is some fantastic information!!! I’ll have to crib that and write it up! but that is amazing I never even though to dig that far!!!!!

    • Previous testing was on Windows 7 64-bit with Service Pack 1.
      I spent testing on Windows XP SP3 32-bit. The results were different from the results on Windows 7.
      Results Qemu 0.14.1 and 0.15.0 turned out the same.
      Columns – parameters of cache.
      Rows – virtual hard disk formats.
      Host OS – Windows XP SP3 32-bit
      Qemu 0.14.1 & 0.15.0 =>
      | raw | fast | fast | fast | fast|
      | qcow | fast | slow | fast | slow|
      | qcow2 | medium* | fast | fast | fast|
      | vdi | fast | fast | fast | fast|
      * – There was a significant slowdown, but still the speed was high enough (about 3 – 5 seconds).
      Since “writethrough” option is the default, it becomes clear why the write speed to a virtual hard drive was high on Windows XP. (maybe it becomes clear)

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