Xen HVM Support

[Ian Campbell]

The following enables support for running SeaBIOS as the virtual BIOS
in a Xen HVM (fully-virtualised) guest.

In this series SeaBIOS is loaded by hvmloader (the Xen early firmware)
rather than directly as was previously tried. This approach turned out
to be far less intrusive on the SeaBIOS side and leaves knowledge of
the virtual hardware setup encapsulated within hvmloader which is
updated in lock step with the hypervisor and associated tools.

BIOS tables are built by hvmloader and passed to SeaBIOS via a simple
in memory data structure. The tables are identified by scanning for
their signatures which is hopefully extensible enough but the core
structure can also be extended as necessary.

The associated hvmloader series was only posted on xen-devel can be
found at:
http://marc.info/?l=xen-devel&m=130692187111154
the most interesting patch is probably:
http://marc.info/?l=xen-devel&m=130692182011054

Ian.