Extend documentation (was: Re: Issue getting my first Xen domU up)

[Roger Pau Monné]

Adding Benedict who wrote the Xen handbook documentation, and
hopefully would be able to fix it :).

On Tue, Feb 05, 2019 at 08:18:05PM +0000, Marcin Cieslak wrote:
> On Tue, 5 Feb 2019, Eric Bautsch wrote:
> 
> > And yes, the qemu-dm-titania.log would have been the place to look. I feel
> > pretty stupid. It says:
> 
> Don't feel stupid. I am using Xen with Dom0 on FreeBSD for months now
> and I didn't know where the qemu logs go - I was able to figure out
> the problem by staring at the configuration file for a long time.
> 
> Therefore your question was very helpful also for me - thanks!

It seems there's one piece missing in the handbook which I didn't
realize, the if_tap module needs to be loaded for QEMU to work.

I suggest the following is added to the handbook:

```
sysrc -f /boot/loader.conf if_tap_load="YES"
```

And then I've also realized the following line:

```
sysrc -f /boot/loader.conf hw.pci.mcfg=0
```

Is only needed for Xen 4.7, but not for Xen 4.11.

Finally it might be interesting to add a reference to the location of
the Xen logs. This should likely be added at the end of the document,
I think something along the lines of:

```
Xen toolstack related logs can be found at /var/log/xen/ be sure to
check the contents of that directory if experiencing issues.
```

Sorry to bother you Benedict, but do you think you could make the
following changes?

Thanks, Roger.