Xen device model support in QEMU

[Kamala Narasimhan <kamala.narasimhan@gmail.com>]

I got the latest qemu repo with xen device model support from -

git://xenbits.xen.org/people/sstabellini/qemu-dm.git

Here are some of the issues I encounter/questions I have -

1) Passing --enable-xen while running ./configure results in

ERROR
ERROR: User requested feature xen
ERROR: configure was not able to find it
ERROR

Turned out there are some interface version compatibilities between
qemu from the above repo and everything else from
staging/xen-unstable.  Tweaking xc_interface_open parameter under "xen
probe" in the configure file got past this problem.

2) Passing --target-list=xen-dm-softmmu to configure resulted in
"ERROR: Target 'xen-dm-softmmu' not recognised" error as target_arch2
is xen and not xen-dm.  Switching to
--target-list=xen-softmmu got me going.  Perhaps this should be fixed
in the configure file if the expectation is to pass xen-dm-softmmu.

3) When I attempt to build after this point I get all kinds of errors
due to interface compatibility mentioned in #1 above.  Is there a
specific version of libxc/libxenstore/libxenctrl etc. and relevant
headers I should be using with this qemu?  If so, that would be good
to know as I would rather switch to a compatible interface than go
about fixing all the resulting build errors.

Kamala