Create a minimal Fedora Rawhide guest

Create a Fedora 20 guest from scratch using virt-builder , fully update it, and install a couple of packages:

$ virt-builder fedora-20 -o rawhide.qcow2 --format qcow2 \
  --update --selinux-relabel --size 40G\
  --install "fedora-release-rawhide yum-utils"

[UPDATE: Starting Fedora-21, fedora-release-rawhide package is renamed by fedora-repos-rawhide.]

Import the disk image into libvirt:

$ virt-install --name rawhide --ram 4096 --disk \
  path=/home/kashyapc/rawhide.qcow2,format=qcow2,cache=none \
  --import

Login via serial console into the guest, upgrade to Rawhide:

$ yum-config-manager --disable fedora updates updates-testing
$ yum-config-manager --enable rawhide
$ yum --releasever=rawhide distro-sync --nogpgcheck
$ reboot

Optionally, create a QCOW2 internal snapshot (live or offline) of the guest:

$ virsh snapshot-create-as rawhide snap1 \
  "Clean Rawhide 19MAR2014"

Here are a couple of methods on how to upgrade to Rawhide

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Fetching Rawhide Kernel builds using koji

To fetch rawhide kernels from Koji (Fedora build system), this is what I do:

Install the group “RPM Development Tools” to get koji packages

$ yum groupinstall "RPM Development Tools" 

NOTE: If you’re using versions < Fedora 19, please do: yum groupinstall "Development Tools"

Find the latest kernel in Rawhide

$ koji latest-pkg rawhide kernel                                                                      
Build                                     Tag                   Built by
----------------------------------------  --------------------  ----------------
kernel-3.10.0-0.rc0.git26.1.fc20          f20                   jwboyer

Download the resultant kernel from the o/p of the above command.

$ koji download-build \
  --arch=x86_64 kernel-3.10.0-0.rc0.git23.1.fc20 

Finally, install it

$ yum localinstall *.rpm 

Search for a specific patch from an upstream PULL request (KVM) in Fedora Rawhide Kernel

Before I use the latest rawhide kernel for a test, I had to ensure some specific patches made into it from KVM upstream GIT PULL request . This is how I tried:

Fetch the Rawhide Kernel SRPM

Install the rawhide SRPM:

 
# Move into SRPMS directory
$ cd ~/rpmbuild/SRPMS 

# Fetch the SRPM
$ wget http://kojipkgs.fedoraproject.org//packages/kernel/3.10.0/0.rc0.git23.1.fc20/src/kernel-3.10.0-0.rc0.git23.1.fc20.src.rpm 

# Install the kernel SRPM
$ rpm -ivh kernel-3.10.0-0.rc0.git23.1.fc20.src.rpm 

First, simpler way

git-describe to the rescue: Each Fedora rawhide kernel changelog has the precise output of Linus’ tree (thanks jwb!). So, let’s run it on the upstream kernel tree.

 
# Clone Linus' tree (or traverse to its path if it already exists)
# git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
$ cd linux 

# Run:
$ git describe
v3.9-11789-ge0fd9af

The above output can be understood as (from git-describe man page): The current head of the “parent” branch is based on v3.9, and is 11789 commits ahead of it; with a hash suffix ge0fd9af: where “-g” (stands for “git”), e0fd9af is the 7-character abbreviation for the tip commit (which was — e0fd9affeb64088eff407dfc98bbd3a5c17ea479)

Now, compare the above tag from the tag mentioned in changelog of Fedora Rawhide Kernel

$ rpm -q kernel --changelog | head -2 
* Thu May 09 2013 Josh Boyer  - 3.10.0-0.rc0.git23.1
- Linux v3.9-11789-ge0fd9af

Second, a more convoluted way to ensure a specific patch is in

Check upstream KVM tree, for the latest commit —
db6ae6158186a17165ef990bda2895ae7594b039

# Clone the upstream KVM git
$ git clone git://git.kernel.org/pub/scm/virt/kvm/kvm.git

# Traverse into its directory
$ cd kvm 

# Get the latest commit ID
$ git log tags/kvm-3.10-1 | head -1
db6ae6158186a17165ef990bda2895ae7594b039 

Now, get details the above commit. Its commit’s short description says: “kvm: Add compat_ioctl for device control API”

$  git log -p db6ae6158186a17165ef990bda2895ae7594b039 
.....
+       .compat_ioctl = kvm_device_ioctl, 

(that’s the first line of change)

Let’s grep for that string in our just installed kernel sources tree

$ cd ~/rpmbuild/SOURCES/ 

# Copy the patch file archive into a temp directory
$  cp patch-3.9-git23.xz /var/tmp/test/ 

# Extract & list it
$ unxz patch-3.9-git23.xz 
$ ls
patch-3.9-git23 

# grep for that specific line
$ grep ".compat_ioctl = kvm_device_ioctl" patch-3.9-git23 
+       .compat_ioctl = kvm_device_ioctl,

So, the above confirms that the patch (and the KVM GIT PULL request is contained in the koji rawhide build.

And the entire PULL request for KVM updates is merged with this commit ID – 01227a889ed56ae53aeebb9f93be9d54dd8b2de8.