Pkg xen devel - Jan 2019 - Bug#776450: Xen PVH support for grub-xen in Buster

On Mon, Jan 07, 2019 at 08:44:50AM +0000, Colin Watson
wrote:
> On Mon, Jan 07, 2019 at 01:58:19AM +0100, Hans van Kranenburg wrote:
> > Ok great. Since I'm not using (and probably not going to use) the
> > multi-stage multiboot things, this is harder for me to help with.
> 
> With any luck I should be able to work that bit out myself, since I
> think stable's Xen has backported PVH support.
So it seems it doesn't quite have enough PVH support.  I get:

  xc: error: panic: xc_dom_core.c:702: xc_dom_find_loader: no loader found:
Invalid kernel
  libxl: error: libxl_dom.c:638:libxl__build_dom: xc_dom_parse_image failed: No
such file or directory
  libxl: error: libxl_create.c:1223:domcreate_rebuild_done: cannot (re-)build
domain: -3
  libxl: error: libxl.c:1575:libxl__destroy_domid: non-existant domain 8
  libxl: error: libxl.c:1534:domain_destroy_callback: unable to destroy guest
with domid 8
  libxl: error: libxl.c:1463:domain_destroy_cb: destruction of domain 8 failed

(I get the same with your recipe based on upstream master, so I don't
think it's a bug in my backport.)

I can upgrade this host to buster at some point in the nearish future,
but not quite right now.

Would you mind trying out the temporary pvh branch of
https://salsa.debian.org/grub-team/grub ?  I'd like to know whether the
resulting grub-xen-host binary package does the right thing, when built
in the ordinary way (I've test-built this branch using sbuild).

-- 
Colin Watson                                       [cjwatson at debian.org]

On 1/7/19 12:48 PM, Colin Watson wrote:
> On Mon, Jan 07, 2019 at 08:44:50AM +0000, Colin Watson wrote:
>> On Mon, Jan 07, 2019 at 01:58:19AM +0100, Hans van Kranenburg wrote:
>>> Ok great. Since I'm not using (and probably not going to use)
the
>>> multi-stage multiboot things, this is harder for me to help with.
>>
>> With any luck I should be able to work that bit out myself, since I
>> think stable's Xen has backported PVH support.
Well, I can help testing of course if you have instructions about what
to do.
> So it seems it doesn't quite have enough PVH support.  I get:
> 
>   xc: error: panic: xc_dom_core.c:702: xc_dom_find_loader: no loader found:
Invalid kernel
>   libxl: error: libxl_dom.c:638:libxl__build_dom: xc_dom_parse_image
failed: No such file or directory
>   libxl: error: libxl_create.c:1223:domcreate_rebuild_done: cannot
(re-)build domain: -3
>   libxl: error: libxl.c:1575:libxl__destroy_domid: non-existant domain 8
>   libxl: error: libxl.c:1534:domain_destroy_callback: unable to destroy
guest with domid 8
>   libxl: error: libxl.c:1463:domain_destroy_cb: destruction of domain 8
failed
> 
> (I get the same with your recipe based on upstream master, so I don't
> think it's a bug in my backport.)
Yeah, you'll need Xen 4.10 or newer.

And Linux 4.17 or newer for PVH and 4.20 for PVH+grub (or Debian 4.19
which has the patches).

Here's what I run on Stretch in production, if you want to run Xen 4.11:
https://salsa.debian.org/xen-team/debian-xen/tree/stretch-backports

Just build it with pbuilder or something, and the output will be this:
https://packages.mendix.com/debian/pool/main/x/xen/
> I can upgrade this host to buster at some point in the nearish future,
> but not quite right now.
Here's the 4.19 domU kernel that I use on Stretch:

https://packages.mendix.com/debian/pool/main/l/linux/linux-image-4.19.0-0.mxbp.1-cloud-amd64_4.19.9-1~mxbp9%2B1_amd64.deb

It's built from:
https://salsa.debian.org/knorrie-guest/linux/tree/debian/4.19.9-1_mxbp9+1
> Would you mind trying out the temporary pvh branch of
> https://salsa.debian.org/grub-team/grub ?  I'd like to know whether the
> resulting grub-xen-host binary package does the right thing, when built
> in the ordinary way (I've test-built this branch using sbuild).
Sure. I'll have a look at it today.

Hans

On 1/7/19 2:13 PM, Hans van Kranenburg wrote:
> On 1/7/19 12:48 PM, Colin Watson wrote:
>> [...]
> 
>> Would you mind trying out the temporary pvh branch of
>> https://salsa.debian.org/grub-team/grub ?  I'd like to know whether
the
>> resulting grub-xen-host binary package does the right thing, when built
>> in the ordinary way (I've test-built this branch using sbuild).
> 
> Sure. I'll have a look at it today.
Ok, I've built it in sid pbuilder.

On dom0 (this is actually a buster one):

-# dpkg -L grub-xen-host |grep bin
/usr/lib/grub-xen/grub-i386-xen.bin
/usr/lib/grub-xen/grub-i386-xen_pvh.bin
/usr/lib/grub-xen/grub-x86_64-xen.bin

In domU I installed grub-xen-bin grub-xen grub2-common grub-common.

Note that:

Installing for x86_64-xen platform.
grub-install: warning: no hints available for your platform. Expect
reduced performance.
Installation finished. No error reported.

...which means that it only has /boot/grub/x86_64-xen with a copy of the
modules. Maybe that's something to think about for the part of the story
that actually expects those modules to be there? Maybe just always throw
all of the three different types in there?

Anyway, the first thing we're testing doesn't rely on that, so let's
continue. In the xen config file, I use...

---- >8 ----
kernel = "/usr/lib/grub-xen/grub-i386-xen_pvh.bin"
type = "pvh"
---- >8 ----

...and yes, blue grub screen and it boots.

Suggestion:
>From usability point of view, it would actually also be nice if
console=hvc0 would be added by default in the GRUB_CMDLINE_LINUX_DEFAULT
for inside the Xen domU.

The default is now "quiet", but if you remove "quiet", it
stays as
quiet, and for a new user, it doesn't have to be super obvious what to
do in this case.

Hans