[fedora-virt] Fedora virt status

Mark McLoughlin markmc at redhat.com
Fri Nov 20 20:02:41 UTC 2009

Fedora 12 Release

Yay! Fedora 12 was released on Tuesday:


Thanks to all who help get this release out!

There was a single response to my call for a "witty tagline" for
Fedora 12, so I went with Avi's "Dirty Dozen" suggestion - it's Fedora
*12* and we have *12* virt features listed so ... :-)


Note also that the marketing folks have posted an interview with some
of the Fedora virt developers here:


  Fedora 12 includes a number of improvements in the field of
  Virtualization. New tools enable system administrators to perform
  nearly impossible - until now - tasks easily. Imagine re-configuring
  a virtual machine off-line, add new hardware to VM with out
  restarting it, migrate to another host without restarting the VMs
  and many other exotic features. Let's hear what developers have to
  say about those wonderful new options.


Justin Forbes announced the availability of a virt-preview repository
for Fedora 12 users:


  A couple of improvements have been made this time around.  Namely
  packages are build with mock instead of koji so that new packages
  can be used a BuildRequires for other new packages.  Also new builds
  are triggered by successful koji builds of tracked packages against
  dist-rawhide, so the process is a bit more automated.

These improvements should make virt-preview a hell of a lot more
useful and manageable. Kudos Justin!

Release Blockers

As with any release, we went through a couple of fire-drills with
last-minute serious blocker bugs:

    rawhide/i386 kvm host corrupts data of guests
    preadv()/pwritev() prototypes are broken on i386 with

    KVM guests on 32 bit hosts were seeing data corruption in some
    circumstances. After huge efforts from Justin Forbes, James Laska
    and Milan Broz to get the issue narrowed down to qemu, yours truly
    bisected it to the introduction of preadv/pwritev support.

    I happened to be sitting around a table with Dan Berrange, Chris
    Wright, Stephen Tweedie, Herbert Xu and Dor Laor at the time and
    all chipped in helping to figure out the issue. Eventually, danpb
    found the issue with glibc's preadv()/pwritev() prototypes in its
    headers and a simple fix sorted the issue out just in time for the

    Now there's a team effort!

Another saga was going on in parallel on the VT-d front:

    swiotlb should be enabled when VT-d setup fails

    This got recognized as a critical issue very late in the release
    as it was realized that there are plenty of users who will have
    VT-d enabled in the BIOS, certain broken BIOSes and >4Gb memory
    (including swap).

    In the end dwmw2's patch was included and tested by multiple
    people, so intel_iommu=on is still the default in Fedora 12.

    DMAR: kernel panic with

    But then this issue came to prominence post-release, and it turns
    out the fix for bug #524808 broke those machines with fault BIOSes
    and <4Gb of RAM. Sometimes you just can't win!

    Lots of folks have been battling away at these bugs including
    David Woodhouse, Chris Wright, Adam Williamson and a whole bunch
    of others.

Mount guest filesystems in the host

Rich Jones continues rocking with yet another cool feature:


  We just built a package called 'libguestfs-mount' in Rawhide which
  lets you mount virtual machines' filesystems on the host, using

Rich may have announced this very quietly, but sit up and take note -
this is damn useful!


DOOM-O-METER: 186 bugs open three weeks ago, only 173 now!

== Ongoing ==

=== kernel ===

    "kvm_run: failed entry, reason 7" when running guest with F11

    Looks like an issue starting a guest on a F11 AMD host.

=== qemu ====

    qemu's system_powerdown doesn't work with Windows XP

    Now that virtinst enables acpi for XP guests, we're noticing that
    'virsh shutdown' has no effect on them. That may be just due to a
    lack of ACPI support in the guest.

    Any use of QEMU's vvfat driver always abort()s the whole process

    Dan Berrange discovered this nasty hack which causes glibc to
    abort qemu.

=== libvirt ===

    restore fails with large files; libvirtd becomes unresponsive

    Charles Duffy reported this issue and proposed a fix. Apparently
    this isn't needed upstream anymore, but we may still need it for

    virsh save hangs in Fedora12 rawhide

    SELinux related issues breaking save/restore.

    SELinux is preventing /usr/bin/qemu-kvm "write" access on sr0

    It looks like we're getting AVCs because qemu is trying to open
    read-only images for writing.

=== python-virtinst ===

    python-virtinst: add a label to newly created disks?

    This has come back full circle again. Now that the anaconda guys
    have refused to do anything about it, our only option is to figure
    out some way of labelling the disk before starting the guest.

=== virt-manager ===

    virt-manager should disable unimplemented reboot option for

    libvirt doesn't implement reboot for KVM (#496537), yet the button
    is still available in virt-manager.

    virt-manager: URL install should prompt to change scratchdir perms

    virt-manager is downloading kernel and initrds to the users home
    directory where qemu cannot read them. Proposal is that
    virt-manager should prompt to change the ACLs on this dir like it
    does for ISOs.

== Resolved ==

=== kernel ===

    KSM bad_page() issue preventing VM startup

    Justin Forbes has cherry-picked a fix from upsteam into the kernel
    in updates.

=== qemu ===

    qemu use-after-free crash in slirp/m_free()

    A couple of days after the F-12 release, we get a report of a very
    obvious crasher in qemu 0.11.0's slirp code. One really does
    wonder how these things get unnoticed until after the release :-)

    qemu-img convert can't handle parallels images above 4GiB

    David Woodhouse sent a patch upstream to fix this.

=== xen ===

    kernel backtrace: possible recursive locking detected on Xen domU

    Apparently this problem just disappeared with a recent 2.6.31

More information about the Fedora-virt mailing list