From PVH to HVM - A simple change in the Advanced Settings box?

A post for General Discussion rather than Support because it is hardly an urgent matter now in October, and I don’t want to distract any of you gurus from more important and urgent business for no good reason when there’re months to go before I get to find out the hard way. This is mainly a matter of curiosity now, so that is why I thought General more appropriately laid back than Support.

The plan is to get on down to the Boxing Day Sales after Christmas and find a replacement ex-demo laptop for this Toshiba Satellite i7 which was itself a shop demo until Boxing Day 2016, so that would make it somewhere around five(5) years old by now I suspect, and I’ve had it for almost four(4), which is a year longer than the tax department tends to fully depreciate computer hardware as far as I remember. Not a bad run, really, but it’s high time to upgrade with or without the high end Qubes 4 requisites. Everything dies, even Toshiba laptops.

This elderly Satellite doesn’t have IOMMU/VT-d / AMD-Vi (I believe the former applies to Intel i7 CPUs), and so I’ve just installed Qubes OS 4.0.3 yesterday with the PVH virtualisation mode.

My hope is that all I will need to do after bringing home my brand new ex-demo laptop and booting this very 4.0.3 system which I am writing on now from external USB HDD, is change the settings in each of the VMs from PV or PVH to HVM, and that’s that.

Not having had the chance to try it before, I would like to ask if others have managed this operation before, and if it is as simple as I hope it will be, or might there be other issues to deal with?

I discovered yesterday that it is not wise to try to change the sys-net template from Fedora-30 to Debian-10 if one wants to maintain network access, even though the option seems quite a simple manoevure at first glance. So, with that in mind, I wonder whether changing all the existing VM’s virtualisation from PV/PVH to HVM when I have the required CPU hardware might be likely to cause any hiccups?

No rush to reply, but just when you’ve got nothing much else to deal with, so that is why this is in General and not Support.
Thanks for reading.

My hope is that all I will need to do after bringing home my brand new ex-demo laptop and booting this very 4.0.3 system which I am writing on now from external USB HDD, is change the settings in each of the VMs from PV or PVH to HVM, and that’s that.

This should be as simple as you describe. I have previously had to pass
through hardware to a VM, simply changing it to HVM from PVH and booting
worked fine.

I discovered yesterday that it is not wise to try to change the sys-net template from Fedora-30 to Debian-10 if one wants to maintain network access, even though the option seems quite a simple manoevure at first glance. So, with that in mind, I wonder whether changing all the existing VM’s virtualisation from PV/PVH to HVM when I have the required CPU hardware might be likely to cause any hiccups?

The debian template may not have the required packages installed for
sys-net, though this is a guest.

A list is available here: https://www.qubes-os.org/doc/templates/minimal/

I’d also recommend installing the fedora-32 template, fedora-30 went EOL
a few months back.

Thank you once again Jarrah. As much as I was reluctant to lose all my un-backed-up bookmarks and AppVMs and menu layouts and have to start again, and as much as I was feeling a bit stubborn in an old-fashioned way about changing from 3.2 to 4 when there was only a few months before the time will come to upgrade hardware, you were right all along, Sir.

I started the first install of 4.0.3 at around 10am yesterday morning, then after my Fedora-Debian wrong turn began again with a fresh install at noon, and had almost everything up and running much like before by 10pm last night.

It wasn’t such a big job after all.

Now the bonus is that I will hopefully have a working 4.0.3 system ready to run from 2021 on when the new hardware is acquired, so it would appear that I would have had to do yesterday’s chore in late December anyway, and now it’s done. Merry Christmas!

—oo0oo—

Fedora-32 eh? Thanks. I’ve mainly kept to Debian-Ubuntu-Mint for the last decade so the Redhat-Fedora strain is not something I’m all that familiar with anymore. The Fedora template is only used here now for sys-net, sys-firewall and a couple of DVMs which I haven’t yet worked out what to do with, so probably not urgent. I shall take your advice a bit more seriously now though, and do some research into what the Fedora upgrade entails. Cheers!

On a 4.0 system with IOMMU, by default all VMs without assigned devices are PVH, and all VMs with an assigned device (sys-net, sys-usb) are HVM. There is a drop-down menu in the setting to change between PV/PVH/HVM, it works.

You may need to apt-get a wifi driver. I’ve been using debian-10 for my sys-net for a long time with no issues.

Thank you for the information regarding defaults for that PV/HVM setting and also especially for the suggestion about a wi-fi driver for debian-10 too.

I’d resigned myself to just running Fedora for the sys-net & -firewall but now you’ve pointed the way, I can see it worth having a go at finding the right driver/s and migrating completely to Debian. Nothing at all against Redhat or Fedora. I started out on Linux with Redhat 6.1, but that was only for servers and I stuck with Win9x for clients back in 1998. Because I couldn’t get graphics to run except with Mandrake, which is now history, AFAIK.

Now I want Debian because I discovered Ubuntu 9.1 Jaunty in 2009 and have been using Debian-based systems for this past decade. Nothing against Fedora though. It’s probably better, actually, but I’m getting a bit old to learn new tricks now unless I really have to.