The "dtb" option sets the filename for the device tree.
If without this option support, "-dtb file" will be converted into
<qemu:commandline> in domain XML file.
For example, '-dtb /media/ram/test.dtb' will be converted into
<qemu:commandline>
<qemu:arg value='-dtb'/>
<qemu:arg value='/media/ram/test.dtb'/>
</qemu:commandline>
This is not very friendly.
This patchset add special <dtb> tag like <kernel> and <initrd>
which is easier for user to write domain XML file.
<os>
<type arch='ppc' machine='ppce500v2'>hvm</type>
<kernel>/media/ram/uImage</kernel>
<initrd>/media/ram/ramdisk</initrd>
<dtb>/media/ram/test.dtb</dtb>
<cmdline>root=/dev/ram rw console=ttyS0,115200</cmdline>
</os>
Signed-off-by: Eric Blake <eblake@redhat.com>