References: jsc#SLE-6262, fate#327048: KVM: Boot Configuration Override (virt-manager)

Subject: guest: Add reorder_boot_order method
From: Marc Hartmayer mhartmay@linux.ibm.com Tue Feb 26 10:56:37 2019 +0100
Date: Wed Mar 6 13:15:38 2019 -0500:
Git: c9d070da4c3d31c3c504f52dbff775483ebf5e35

Add `reorder_boot_order` method to Guest class. It sets the boot order
of the passed `dev` to `boot_index` and adapts all other boot indices
of the guest accordingly.

Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>

Index: virt-manager-2.1.0/virtinst/guest.py
===================================================================
--- virt-manager-2.1.0.orig/virtinst/guest.py
+++ virt-manager-2.1.0/virtinst/guest.py
@@ -257,6 +257,40 @@ class Guest(XMLBuilder):
         return self.__osinfo
     osinfo = property(_get_osinfo)
 
+    def reorder_boot_order(self, dev, boot_index):
+        """Sets boot order of `dev` to `boot_index`
+
+        Sets the boot order for device `dev` to value `boot_index` and
+        adjusts all other boot indices accordingly. Additionally the
+        boot order defined in the 'os' node of a domain definition is
+        disabled since they are mutually exclusive in libvirt.
+
+        """
+        # unset legacy boot order
+        self.os.bootorder = []
+
+        # Sort the bootable devices by boot order
+        devs_sorted = sorted([device for device in self.get_bootable_devices()
+                              if device.boot.order is not None],
+                             key=lambda device: device.boot.order)
+
+        # set new boot order
+        dev.boot.order = boot_index
+
+        next_boot_index = None
+        for device in devs_sorted:
+            if device is dev:
+                continue
+
+            if device.boot.order in [next_boot_index, boot_index]:
+                next_boot_index = device.boot.order + 1
+                device.boot.order = next_boot_index
+                continue
+
+            if next_boot_index is not None:
+                # we found a hole so we can stop here
+                break
+
     def set_os_name(self, name):
         obj = OSDB.lookup_os(name)
         if obj is None: