Re: [Xen-users] Unable to start a pvh guest

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Sep 01, 2017 at 03:24:53PM +0800, Zihan Yang wrote:
> Hi all,
> 
> I'm trying to start a pvh guest on debian 8.2(whose kernel is
> 3.16.43-2+deb8u3) with xen 4.5.0, the guest is a compiled linux 4.12.10
> kernel(pvh support enabled). However, the xen could not parse the config
> correctly, saying
>     xc: error: panic: xc_dom_core.c:877: xc_dom_parse_image: unsupported
> feature requested: Invalid configuration
>     libxl: error: libxl_dom.c:583:libxl__build_pv: xc_dom_parse_image
> failed: No such file or directory
>     libxl: error: libxl_create.c:1121:domcreate_rebuild_done: cannot
> (re-)build domain: -3
> 
> The problem is that when I change to linux 4.7, xen4.5.0 could successfully
> create the VM, although it got stuck when booting, I got only one line
> output,
>     (XEN) irq.c: 380: Dom1 callback via changed to Direct Vector 0xf3
> 
> I've got one successful try with xen 4.9.0 and linux cloned from git://
> git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git
> 
> I wonder if pvh is not fully supported in xen 4.5.0? Do I have to switch to
> xen 4.9.0 to start a pvh guest?

Hello,

The PVH story is kind of messy. IIRC Xen 4.5 has support for PVHv1,
which is now removed in newer Xen versions in favor of the new
implementation, PVHv2.

So, if you want to try PVH, you should try PVHv2, and then you need a
recent Xen version (I would recommend 4.9). In which case you also
need a recent Linux kernel version (I'm not really sure in which Linux
version PVHv2 was introduced).

I would recommend using Xen 4.9 with Linux 4.12 if possible, and then you
will have to create the PVH guest by adding the following to your
config file:

builder='hvm'
device_model_version='none'

I'm currently working on providing a better toolstack interface in
order to create PVHv2 guests. Please note that the above way to create
a PVHv2 guest is not stable, it will be hopefully replaced in 4.10
with a stable interface.

Roger.

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