Virtualization
In this section, we cover discussion on the @et-mgmnt-tools-list, @fedora-xen-list, and @libvirt-list of Fedora virtualization technologies.
Contributing Writer: Dale Bewley
Enterprise Management Tools List
This section contains the discussion happening on the et-mgmt-tools list
Fedora Virtualization List
This section contains the discussion happening on the fedora-virt list.
New Release libguestfs 1.0.10
Richard Jones
announced[1] release 1.0.10 of 
libguestfslibguestfs has progressed very far very fast.
"libguestfs is a library for accessing and modifying guest disk images. Amongst the things this is good for: making batch configuration changes to guests, getting disk used/free statistics (see also:
Features in 1.0.10 include:
- bindings for: C, C++, Perl, Python, OCaml, Ruby, Java and shell scripting
- KVM support
- QEMU binary is completely configurable at compile & runtime
- ext4 support
- support for uploading and downloading arbitrary-sized files
- support for uploading and downloading tar and tar.gz content
- support for querying size of block devices, setting r/o
- support for reading ext2/3 superblocks
- stat, lstat, statvfs commands
- commands to mount filesystems read-only
- run arbitrary commands from the guest
- file(1) command
- readline in guestfish with history and tab completion
- guestfish 'edit' command
- big documentation improvements, including more on the internals
- pkgconfig file
Richard posted some example uses[4]
of the libguestfs command line tool called guestfish.
Non-root User Image Locations
Robert Day
asked[1]
"by default, new VM images are created in
/var/lib/libvirt/images, and that directory is not accessible to
non-root users."
There are two classes of libvirt driver connection - Privileged, per-host connections - Unprivileged, per-user connections Xen provides a per-host connection. UserModeLinux and QEMU provide both (qemu:///system and qemu:///session). VirtualBox just proivides a per-user instance (vbox:///session) and so on. Now by default in Fedora, when connecting to QEMU, virt-manager will use the privileged per-host connection, so VMs end up in the system directory /var/lib/libvirt/images. Our goal (perhaps for F12) should be for local desktop virt use cases to use the unprivileged QEMU connection qemu://session by default, and have VM disk images stored in your home directory
> How would we allow KVM access? Unix groups or something else? Two options - A UNIX group for /dev/kvm - Just make it world writable In theory now KVM no longer pins all guest RAM into host RAM, it is reasonable safe to allow users to access it without any restrictions. (eg option 2) Will need to confirm with KVM developers if this is really so, but that was the intention last time i asked them.
Historically SELinux has wanted images in particular locations. With the introduction of SVirt in libvirt, we have much more advanced SELinux integration and will in fact automatically re-label images to match the needs of a VM. So allowing arbitary locations *and* still being in compliance with SELinux policy is now practical
Fedora Xen List
This section contains the discussion happening on the fedora-xen list.
Dom0 Kernel Not Before 2.6.31
The upstream Xen dom0 work done by Jeremy Fitzhardinge has been cleaned up and reorganized[1] into
- xen-tip/master - Known-working branch, with only tested changes
- xen-tip/next - Current bleeding edge; should at least compile
Michael Young built[2] a new experimental dom0 kernel "version (2.6.30-0.1.2.21.rc3.xendom0.fc12) is based on the Fedora devel kernel branch and xen-tip/next branch from the pvops kernel repository." This kernel may be found in Michael's yum repo[3].
Michael added that "very few xen patches made it into 2.6.30, just bugfixes and tidy ups, so we are waiting at least until 2.6.31[4] for mainline dom0 support."
Libvirt List
This section contains the discussion happening on the libvir-list.