I have it working, got it sorted out a couple of weeks ago. I installed a newer kernel (5.3.0) from the ubuntu repository along with grub-pc, and switched over to PVH no problem. Switching between PV and PVH is just a single command in Xen, so pretty easy to switch between them if booting fails. Hope that helps, Anna On Tue, 4 Jan 2022, at 15:28, Paul Tansom wrote:

Hi Paul, On Thu, Jan 06, 2022 at 10:42:20PM +0000, Paul Tansom wrote: I think what I would do is first try pvshim, achieved by setting either your architecture or virtmode to the same as what it currently is: xen shell> arch i686 xen shell> shutdown xen shell> boot The reason for that is that a) it's most likely to Just Work, and b) it's a change that will be forced on you in 11 days anyway if you stay as is, also if you go to PVH mode and then switch BACK, it will actually be pvshim as well. If you are at all worried that it might not work, ask BitFolk to do the switch. That doesn't make it any more/less likely to work but if it doesn't we can quickly roll the change back and try to see why. Once you've got that done, you can just leave it there, or you could try switch to PVH: xen shell> virtmode pvh xen shell> shutdown xen shell> boot If *that* doesn't work then you can just switch back to where you were before: xen shell> virtmode pv xen shell> boot This virtualisation mode is just a different way of booting, it will either work or not; there is not any danger to your data so I don't think there is any need to take a special backup (always have normal backups!). And you can just switch it back yourself if it doesn't work. Switching to PVH is a simple procedure that doesn't require any changes to your VM (assuming new enough kernel and grub2), so I would just do it if you can stand a reboot for pvshim and then a reboot for PVH. Having a new account to install into is the same work, but your stuff keeps working on the other one while you do it, so there is that. Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting

Hi Paul, On Tue, Jan 04, 2022 at 02:28:07PM +0000, Paul Tansom wrote: Yeah :) I meant more that upgrading hasn't been an issue since there never has been an upgrade path for 32-bit Ubuntu 18.04. It's more a question of assumptions. We've had a bunch of customers on Debian assume that upgrades will just work, and a 32-bit buster to bullseye upgrade in PV mode DOES appear to work, until they reboot! So it's a case of it being an unexpected problem and scary if you don't know that you just have to switch to PVH mode. The simplest thing you can do is try out the pvshim by doing this: xen shell> arch i686 (even though you are already on i686) That will implement the config change to change you to pvshim, the same change that is going to happen for all the remaining 32-bit PV guests on 18 January. I have not yet seen this fail to work, but trying it ahead of time is still a good idea as it will take effect from your next boot so best to be prepared for it as opposed to it happening just whenever you next have need to reboot. So then: xen shell> shutdown xen shell> boot If you are already on a kernel newer than 4.19.0 and running grub2 (boots with /boot/grub/grub.cfg) then the next easiest thing would be instead to switch to PVH mode. xen shell> virtmode pvh xen shell> shutdown xen shell> boot The *best* thing would be 64-bit PVH mode, but that is either some hassle installing a 64-bit kernel, lots more hassle doing a full cross-grade, or some work setting up a whole new VM. Yes and it does not work because Ubuntu 18.04 comes with a 4.15.x kernel: https://tools.bitfolk.com/wiki/PVH#Ubuntu If you can get onto a newer kernel such as by installing the linux-generic-hwe-18.04 package or one of the other various packaged newer kernels then it should work; we've had only successful reports from customers doing this. You then would get to live out the remaining support life of 18.04 (bearing in mind that only a subset of the packages in "main" do have support). The issue now is that we no longer support 32-bit PV mode guests so there is purposefully no way to switch back to that. When you select 32-bit PV it will actually do pvshim; the only other option is 32-bit PVH. Those still running as 32-bit PV are in a transitional state now that will be resolved in 2 weeks by being forcibly moved to pvshim. As I say, we haven't yet encountered a failure on switching to pvshim, but not every combination has been tested so we can't definitively say it will work. If you want us to do the switch for you then that's fine, just drop an email to support(a)bitfolk.com asking for that and saying when to do it. The advantage being that we will be able to quickly roll the change back should there be a problem. When you say "switching to 64bit", do you mean by means of a new account that you will migrate your stuff into? I ask because I wouldn't necessarily recommend the other options. Just installing to a 64-bit kernel is easy but given there is no upgrade path for the 32-bit userland with Ubuntu, so it's not a good long term plan. That leaves a full cross-grade to 64-bit which I would say is more work than migrating and things are broken while you do it. Hopefully that explains the situation and your options but if there's anything else that's unclear please do let us know! Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting