Re: CentOS 8 Install as DOMU in PV Environment

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use the kernel from elrepo, it has xen support build in...


Am 19.09.2020 19:26, schrieb Chris Wik:
We tried to get CentOS 8 domU working in PV mode as well but did not
have any success and ended up deploying it in HVM mode.

The reason OP have was lack of hardware support for HVM. This wasn't
our rationale for wanting to run in PV mode. Our rationale was that we
prefer to deploy CentOS 7 VMs on LVs which are formatted and deployed
from an image on dom0 and don't have any partition table. This makes
snapshotting, mounting, backing up and migrating very simple. We have
written a number of scripts over the years that needed extensive
modification to work with HVM VMs but in the end we ended up doing it
because we couldn't get PV mode working. And we accepted that HVM is
the future so might as well take the opportunity to adapt our ways.

If anyone manages to get PV mode working I'd still like to know.


On September 19, 2020 7:08:28 PM GMT+02:00, "Radosław Piliszek"
<radoslaw.piliszek@xxxxxxxxx> wrote:


In general, PV tends not to be supported in newer distribution
This is mostly due to HVM performance and flexibility nowadays,
just was not the case back in the days when PV ruled.

I am curious why you are trying PV.


On Sat, Sep 19, 2020 at 6:41 PM 9f9dcad3f78905b03201--- via
CentOS-virt <centos-virt@xxxxxxxxxx> wrote:


Just wanted to check one last time before letting this thread die.

I am curious if anyone has gotten CentOS 8 to work in a PV Xen


<9f9dcad3f78905b03201@xxxxxxxxxx> wrote:

I have successfully installed CentOS 7 on a PV environment, and have
been trying to see if I can can get a CentOS 8 install running.

Hardware does not support virtualization extensions, hence the PV
environment and I cant do HVM for the install then migrate.

My understanding is that PV support is in the kernel, and that the
distro of Linux shouldn&#39;t technically matter. But currently when
trying to &quot;PXEBoot&quot; using a CentOS 8 kernel and ram image
I get a near instant crash for an invalid kernel.

I tried to get around the issue by using DOM0 kernel and Ram Disk
for the install (DOM0 is Debian 10), having the boot progress until
it reaches the following, looping ISCSI error:

&gt;[ OK ] Reached target Slices.
&gt; Starting Create Static Device Nodes in /dev...
&gt;[ OK ] Started iSCSI UserSpace I/O driver.
&gt;[ OK ] Started Setup Virtual Console.
&gt; Starting dracut cmdline hook...
&gt;[ OK ] Started Apply Kernel Variables.
&gt;[ OK ] Stopped iSCSI UserSpace I/O driver.
&gt; Starting iSCSI UserSpace I/O driver...

I have also tried the CentOS 7 kernel Ram Disk with the same

I even tried installing CentOS 7 clean, then upgrading in place (by
unofficial and unsupported means) and was left with an error that
pygrub couldnt find the partition with the kernel.

Is this is a bug, or is PV just not supported? Or am I doing
something wrong?

Config for the install is below:

&gt;# Kernel paths for install
&gt;#kernel =
&gt;kernel = &quot;/vmlinuz&quot;
&gt;#ramdisk =
&gt;ramdisk = &quot;/initrd.img&quot;
&gt;extra=&quot;modules=loop,squashfs console=hvc0&quot;
&gt;# Path to HDD and iso file
&gt;disk = [
&gt; #&#39;file:/vmdisk0,xvda,w&#39;
&gt; &#39;format=raw, vdev=xvda, access=w,
&gt; ]
nameserver= [1]&quot;
&gt;# Network configuration
&gt;vif = [&#39;bridge=xenbr0&#39;]
&gt;#DomU Settings
&gt;memory = 3072
&gt;name = &quot;centos-8.2&quot;

Thank you to all.


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Chris Wik
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