[fedora-virt] Fedora virt status

Mark McLoughlin markmc at redhat.com
Fri Sep 11 15:22:05 UTC 2009

Fedora 12 Schedule

The Fedora 12 release is looming large. At this stage, all efforts
should be focused on polishing off everything for the final release.

  2009-09-17 Virt Test Day (6 days)
  2009-09-29 Final Development Freeze (18 days)
  2009-10-28 Release Candidate Compose (47 days)

Fedora Test Day

Next Thursday, September 17th, we will be holding be holding Fedora
Test Day in order to test all the latest Fedora 12 virt goodies:


  General Virt

    * PXE booting
    * Live Migration
    * The qcow2 image format


    * KSM
    * Huge page backed memory
    * NIC hotplug
    * Stable guest ABI


    * libguestfs
    * VirtStorageManagement
    * Network_Interface_Management
    * VirtTCK
    * VirtPrivileges

  Hardware Enablement

    * SR-IOV
    * VT-d

Preparations for the day are still in their early stages, so if you
want to help out, please dive right in.

Most importantly, though, please do make an effort to turn up on the
day, grab some test cases and report bugs!

KSM Tuning Daemon

On the fedora-virt list, Dan Kenigsberg and Dan Berrange discussed
creating a KSM tuning service:


  An unattended host running a variable number of qemu-kvm's needs to
  tune ksm automatically, since when memory is tight, it's better to
  spend more cpu on merging pages. In more relaxed cases, it's just a
  waste of time.

  The attached service tries to do just that.

  It monitors how much memory is used by qemu-kvm processes, and
  starts ksm when a threshold is passed. Ksm usually manages to free
  up some memory.

This relates to the new KSM feature in Fedora 12:



Dale Bewley continues to churn out excellent virt updates for Fedora
Weekly News:


Dale also posted a sneak preview of the extensive virtualization
section for the Fedora 12 release notes:


Xen Dom0

Huge amounts of activity is going on the fedora-xen list around
testing out the latest Xen pv_ops Dom0 kernels. It's all too much to
summarize here, so if you're interested, take a look a the list



DOOM-O-METER: 214 open bugs now, 217 three weeks ago

The Fedora 12 blocker list is:


and the Fedora 12 target list is:


All these queries can be found on:


Ongoing Bugs

== misc ==

     Directory permissions on volume group directory too restrictive

     The change to fix volume group directory permissions is still
     blocking on a change over to udev. Time is getting tight for

== kernel ==

     virtio_net page allocation failure

     A report of a 2.6.29 virtio_net oops which Rusty recently fixed
     in 2.6.31.

     rotational mode is much faster for virtio-blk disks, but uses
     non-rotational mode by default

     Christoph is having trouble reproducing this issue.

     Unable to boot using qemu-kvm and gPXE from virt-preview

     This issue should be fixed in which hopefully will
     appear in F-11 updates soon.

== qemu ==

     qemu-kvm exits when initializing MSI-X fails on older kernels

     virtio's MSI-X support causes qemu to exit if the kernel does not
     support it. This is now fixed in rawhide by backporting a fix
     from upstream.

     QEMU does not exit if it can't attach to the host USB device

     Dan Berrange notes that qemu doesn't give the user any useful
     error it fails to pass through a host USB device to the guest.

    QEMU threads should share the same I/O context
    Implement support for CLONE_IO

    Uli doesn't think CLONE_IO should be a thread attribute and has
    closed the glibc bug as WONTFIX. The suggestion now is to make
    this a process-wide attribute configurable with prctl().

    qemu slows down dramatically using the SDL graphics backend and
    ac97 sound driver

    It looks like there may be something specific to SDL and ac97
    causing qemu to slow down hugely in Fedora 11.

== libvirt ==

     libvirt is using untrusted 'info vcpus' PID data for already
     running VM after libvirtd restart

     Dan Berrange points out that if a qemu process is compromised, it
     can cause libvirtd to kill another process.

     libvirt/netcf loads modprobe.conf and others - AVC messages
     (preventing libvirtd (virtd_t) "getattr" modules_conf_t)

     David Lutterkort thought it may be possible to get bonding to work
     without modifying modprobe.conf, but that turns out not to be the
     case so we need the selinux-policy to allow it.

     libvirt should check for -soundhw support; qemu-system-sparc does
     not have soundhw support

     It turns out that the sparc target does not have -soundhw
     support. We need libvirt to detect that.

Resolved Bugs

== misc ==

    Guest clock is running aprox. 3 seconds before host clock.

    Now that the kernel is configured with CONFIG_RTC_HCTOSYS,
    initscripts runs hwclock --systz rather than --hctosys, which in
    turn means that the hwclock isn't incorrectly introducing an
    offset between the guest and host clocks.

== kernel ==

    KSM breaks encryption 157 > kernel > 139 - KSM support now

    Andrea tracked down and fixed this KSM blocker and Justin pushed
    the fix to rawhide.

== qemu ==

    kvm forgets to close /proc/meminfo when hugepages are active

    F-11 qemu-kvm is leaking a /proc/meminfo when using huge
    pages. Fixed by backporting a change to use statfs rather than

    qemu locks up at shutdown with sdl audio driver

    It appears several users are using qemu with QEMU_AUDIO_DRV=pa in
    order to get working sound. F-11 and F-12 are now switched over to
    used this backend by default.

    qemu segfault when VNC client disconnects
    qemu VNC :: xterm inside VM shows garbled text

    Fixes for both of these Fedora 11 bugs have now been backported
    and will appear in updates shortly.

== libvirt ==

    selinux policy update needed :: libvirt has moved the location of
    the qemu monitor socket

    libvirt has moved where the monitor socket is created, so the
    selinux policy needed updating. This is fixed in rawhide now.

    unable to start guest: qemu: could not open serial device 'pty'

    This turned out to be caused by incorrect permissions on
    /dev/ptmx. We're still not sure how that came about.

    libvirtd should chown dirs when qemu configured to run as

    Dan Berrange fixed this upstream for libvirt-0.7.1.

    RFE: libvirt should support KVM huge page backed memory

    Dan Berrange polished off John Cooper's patch and pushed it in
    time for libvirt-0.7.1.

    libvirt always places IDE disks before virtio/scsi disks

    A fix for this has been committed upstream and will be pulled into
    F11 soon.

== xen ==

    2.6.31-rc1 xen domU crashes early during boot

    This Xen DomU pv_ops blocker should now be fixed in rawhide thanks
    to a patch from Jeremy Fitzhardinge.

    kernel backtrace: possible recursive locking detected on Xen domU

    A kernel lockdep warning seen under F-12 Xen DomU.

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