SLES 15 seems to work well as a PV guest

[Harry Waddell <waddell%caravaninfotech.com@localhost>]

I've had a LOT of issues with SLES 12 guests and have been running them as HVM guests
as a result. As of xen 4.8.3, I've even had to convert some of my newer SLES 11 systems 
to HVM as well. Adding insult to injury, I've had to disable the PVHVM drivers on the HVM 
guests too. Even with all the special care I've given these systems, they tend to hang 
a lot more than 100+ non-netbsd domUs I run. 

As a very pleasant surprise, SLES 15 seems quite PV friendly on a NetBSD 7-release dom0
with both xen 4.6.3 and 4.8.3. Just boot the install kernel PV and do a network install and 
everything just seems to work. For example I zero out the unused blocks before making a
backup of the LVM post initial setup:

dd if=/dev/zero of=foofile bs=1024k; rm -rf foofile ; poweroff
dd: error writing 'foofile': No space left on device
16087+0 records in
16086+0 records out
16867397632 bytes (17 GB, 16 GiB) copied, 37.6223 s, 448 MB/s

which is pretty good given that writing to an lvm device from dom0 yields about 500MB/s.

RHEL/Centos 7.x and Ubuntu 16 continue to work well in PV as before. 

HW