[CentOS-virt] CentOS 8 Install as DOMU in PV Environment

Sun Sep 20 11:02:45 UTC 2020
Christoph <mangel at gmx.de>

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

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Greetz

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.
>
> Chris
>
> On September 19, 2020 7:08:28 PM GMT+02:00, "Radosław Piliszek"
> <radoslaw.piliszek at gmail.com> wrote:
>
>> Hi,
>>
>> In general, PV tends not to be supported in newer distribution
>> releases.
>> This is mostly due to HVM performance and flexibility nowadays,
>> which
>> just was not the case back in the days when PV ruled.
>>
>> I am curious why you are trying PV.
>>
>> -yoctozepto
>>
>> On Sat, Sep 19, 2020 at 6:41 PM 9f9dcad3f78905b03201--- via
>> CentOS-virt <centos-virt at centos.org> wrote:
>>
>> All,
>>
>> 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
>> environment.
>>
>> Thanks.
>>
>> <9f9dcad3f78905b03201 at bcirpg.com> wrote:
>> All,
>>
>> 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't technically matter. But currently when
>> trying to "PXEBoot" 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:
>>
>> >[ OK ] Reached target Slices.
>> > Starting Create Static Device Nodes in /dev...
>> >[ OK ] Started iSCSI UserSpace I/O driver.
>> >[ OK ] Started Setup Virtual Console.
>> > Starting dracut cmdline hook...
>> >[ OK ] Started Apply Kernel Variables.
>> >[ OK ] Stopped iSCSI UserSpace I/O driver.
>> > Starting iSCSI UserSpace I/O driver...
>>
>> I have also tried the CentOS 7 kernel Ram Disk with the same
>> results.
>>
>> 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:
>>
>> ># Kernel paths for install
>> >#kernel =
>> "/var/opt/xen/ISO_Store/Centos8PXEBoot/vmlinuz"
>> >kernel = "/vmlinuz"
>> >#ramdisk =
>> "/var/opt/xen/ISO_Store/Centos8PXEBoot/initrd.img"
>> >ramdisk = "/initrd.img"
>> >extra="modules=loop,squashfs console=hvc0"
>> >
>> ># Path to HDD and iso file
>> >disk = [
>> > #'file:/vmdisk0,xvda,w'
>> > 'format=raw, vdev=xvda, access=w,
>> target=/dev/mapper/vg_1-virtualmachine',
>> > ]
>> >
>> >extra="ksdevice=
>> inst.repo=https://mirror.jaleco.com/centos/8.2.2004/isos/x86_64/
>> nameserver=1.1.1.1 [1]"
>> >
>> ># Network configuration
>> >vif = ['bridge=xenbr0']
>> >
>> >#DomU Settings
>> >memory = 3072
>> >name = "centos-8.2"
>>
>> Thank you to all.
>>
>> -------------------------
>>
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>> CentOS-virt at centos.org
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>>
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>>
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>> CentOS-virt at centos.org
>> https://lists.centos.org/mailman/listinfo/centos-virt
>
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> --
> Chris Wik
> Anu Internet Services
> www.cwik.ch [2] | www.anu.net [3]
>
> Links:
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> [2] http://www.cwik.ch
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