Red Hat Bugzilla – Bug 852334
[Doc] RFE: Doc for virt-v2v can be confusing -> virt-v2v may install a new kernel
Last modified: 2016-02-19 10:19:25 EST
Description of problem:
The virt-v2v guide can cause confusion. "virt-v2v may install a new kernel...". It should be explained when this happens and why. Additionally there should be explained how to circumvent a kernel update.
Background: Some people are stuck to a particular Kernel Version because of some nasty software depending on it.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
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Hi Richard and Pino,
I'd like to add a bit more detail on the 'virt-v2v may install a new kernel'  topic for the RHEL6 V2V Guide, and am hoping you can help with some questions...
* In what situation would virt-v2v install a new kernel? Is it only when converting a VM using a Xen para-virtualized kernel? Also, I came across the following bit of info later in the guide; is it correct, and is this only circumstance when the new kernel install would happen?:
"If your guest uses a Xen para-virtualized kernel (it would be called something like kernel-xen or kernel-xenU), virt-v2v will attempt to install a new kernel during the conversion process. You can avoid this requirement by installing a regular kernel, which will not reference a hypervisor in its name, alongside the Xen kernel prior to conversion. You should not make this newly installed kernel your default kernel, because Xen will not boot it. virt-v2v will make it the default during conversion."
* Is there any way the user can opt out of the new kernel installation, ie. installing virtIO drivers on the existing kernel, etc?
 ie. Step 1 in https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/V2V_Guide/index.html#idm37606992
Dayle, do you really want to update the documentation for virt-v2v
in RHEL 6? We are strongly encouraging everyone to move to the
RHEL 7 version (virt-v2v-1.28.1), and will soon publish an appliance
that RHEL 6 customers can use (for free) to run the new virt-v2v on
their existing RHEL 6 systems.
I am inclined to close this as WONTFIX.
For the old version of virt-v2v:
The paragraph "If your guest ..." is accurate for old virt-v2v.
In old virt-v2v you can opt out of kernel installation by editing
the configuration file, but if you do that, conversion will just
fail. Fundamentally you need a non-Xen kernel in order to run
guests on KVM, so if they are stuck with a particular Xen kernel
there's no way the guest can be made to work on KVM.
For the new (RHEL 7) version of virt-v2v:
It never installs a new kernel. Instead it checks the already
installed kernels. If none of them is suitable, you'll get an error
message and conversion will fail. If a kernel is suitable but it
is not the currently selected boot kernel, then virt-v2v will
change the selected boot kernel to the suitable one.
We also publish guidance in the manual about the minimum
versions of kernels and other packages required: