Libvirt domain XML allows only local filepaths to specify a loader element
or its matching NVRAM. Given that VMs may themselves move across hypervisor
hosts, it should be possible to allocate loaders/NVRAM disks on network storage
for uninterrupted access.

This series extends the loader & NVRAM disk elements to be described as
virStorageSource* elements, as discussed in :
https://www.redhat.com/archives/libvir-list/2018-March/msg01721.html

Sample XML with new annotation:

<loader readonly='yes' type='pflash' backing='file'>
  <source file='/usr/share/OVMF/OVMF_CODE.fd'/>
</loader>
<nvram backing='network'>
  <source protocol='iscsi' name='iqn.2013-07.com.example:iscsi-nopool/0'>
    <host name='example.com' port='6000'/>
  </source>
</nvram>

References:
----------
v0/ Proposal: https://www.redhat.com/archives/libvir-list/2018-March/msg01721.html.v1
v1: https://www.redhat.com/archives/libvir-list/2018-April/msg02024.html
v2: https://www.redhat.com/archives/libvir-list/2018-May/msg00948.html

Changelog:
---------
Changes since v2:
- Consolidated patches with related data structures to avoid build breakage.
- Passes make check & make syntax-check.

Prerna Saxena (4):
  Schema: Introduce XML schema for network-backed loader and nvram
    elements.
  Loader: Add a more elaborate definition.
  Test: Add a test snippet to evaluate command line generation for   
    loader/nvram specified via virStorageSource
  Documentation: Add a blurb for the newly added XML snippets for loader
    and nvram.

 docs/formatdomain.html.in                      |  36 +++-
 docs/schemas/domaincommon.rng                  | 108 +++++++++--
 src/bhyve/bhyve_command.c                      |   6 +-
 src/conf/domain_conf.c                         | 250 +++++++++++++++++++++++--
 src/conf/domain_conf.h                         |  11 +-
 src/qemu/qemu_cgroup.c                         |  13 +-
 src/qemu/qemu_command.c                        |  21 ++-
 src/qemu/qemu_domain.c                         |  31 ++-
 src/qemu/qemu_driver.c                         |   7 +-
 src/qemu/qemu_parse_command.c                  |  30 ++-
 src/qemu/qemu_process.c                        |  54 ++++--
 src/security/security_dac.c                    |   6 +-
 src/security/security_selinux.c                |   6 +-
 src/security/virt-aa-helper.c                  |  14 +-
 src/vbox/vbox_common.c                         |  11 +-
 src/xenapi/xenapi_driver.c                     |   4 +-
 src/xenconfig/xen_sxpr.c                       |  19 +-
 src/xenconfig/xen_xm.c                         |   9 +-
 tests/qemuxml2argvdata/bios-nvram-network.args |  31 +++
 tests/qemuxml2argvdata/bios-nvram-network.xml  |  42 +++++
 tests/qemuxml2argvtest.c                       |   1 +
 21 files changed, 606 insertions(+), 104 deletions(-)
 create mode 100644 tests/qemuxml2argvdata/bios-nvram-network.args
 create mode 100644 tests/qemuxml2argvdata/bios-nvram-network.xml

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