** Andy Smith <andy@???> [2022-01-04 19:50]:
<snip>
> > I'm reading up with a plan to either switch over manually (trying
> > to get my head around the instructions and fallback options if it
> > goes wrong)
>
> 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.
>
> > So, some quick questions:
> >
> > - has Ubuntu 18.04 i686 been tested under PVH?
>
> 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).
As it happens I'm already running on a HWE kernel, so that's
encouraging. I'm not planning to life out the remaining support life,
I've been planning moving to a 64-bit install for rather too long now
with plans to make use of Docker. With some of the changes I'm preparing
for it would be nice to go in clean with them rather than rebuild what I
have on 64-bit and then mess around. That said, just getting to 64-bit
is rapidly becoming the preferred option!
> > - a previous email talked about needing support if the switch on
> > an existing 32bit goes wrong, but the PVH web page talks about
> > switching back; am I right in thinking that you can switch back
> > and then get support or is the support to get your VPS working
> > again?
>
> 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@???
> 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.
Thanks, I'll let you know. My thoughts were that as one of those
languishing on a legacy setup I'd get my finger out with planned changes
and save you the hassle, particularly as if I'd got my plans sorted
sooner I'd already be 64-bit PVH - but there you go, with the timeliness
of my project I should be running a government one ;-)
> > Switching to 64bit is my plan, with 32bit PVH as a temporary fall
> > back, so just trying to get my ducks in a row first.
>
> 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.
That's the one, I should have been clearer. I read a few posts about the
other options and really didn't like the idea - far too much to go wrong
and potential problems lurking for later.
> 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!
No, I think that covers things very well thanks.
** end quote [Andy Smith]
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