Bug #172812 - Document new automatic uninstallation behavior in the

"Conflict Avoidance" section.

svn path=/main/trunk/; revision=9948

diff --git a/doc/dependency_resolution/task_scheduling.docbook b/doc/dependency_resolution/task_scheduling.docbook
index 8979a9f628e12706af3e3363234cf9c3434fa451..d9ecec168beca5373850436203ce9055ce55eaf2 100644 (file)
--- a/doc/dependency_resolution/task_scheduling.docbook
+++ b/doc/dependency_resolution/task_scheduling.docbook
@@ -12,11 +12,38 @@
 <sect1 id='dependency-resolution-task-scheduling-conflict-avoidance'>
        <title>Conflict Avoidance</title>
        <para>
-       In some cases it is possible to adjust package installation order
-       to avoid having two conflicting packages installed simultaneously.
+       Sometimes a package installation order exists such that it is
+       possible to avoid having two conflicting packages installed
+       simultaneously. If a currently installed package conflicts with a
+       new package that is planned to be installed, it may be possible to
+       solve the conflict by replacing the installed package with a
+       different package that occupies the same slot.
        </para>
        <para>
-       TODO: Automatically uninstall packages when necessary to avoid conflicts.
+       In order to avoid a conflict, a package may need to be uninstalled
+       in advance, rather than through replacement. The following constraints
+       protect inappropriate packages from being chosen for automatic
+       uninstallation:
+       <itemizedlist>
+       <listitem>
+       Installed packages that have been pulled into the current dependency
+       graph will not be uninstalled. Due to
+       <link linkend='dependency-resolution-package-modeling-dependency-neglection'>
+       dependency neglection</link>, other checks may be necessary in order
+       to protect inappropriate packages from being uninstalled.
+       </listitem>
+       <listitem>
+       An installed package that is matched by a dependency atom from the
+       "system" set will not be uninstalled in advance since it might not
+       be safe. Such a package will be uninstalled through replacement.
+       </listitem>
+       <listitem>
+       An installed package that is matched by a dependency atom from the
+       "world" set will not be uninstalled if the dependency graph does not
+       contain a replacement package that is matched by the same dependency
+       atom.
+       </listitem>
+       </itemizedlist>
        </para>
 </sect1>
 <sect1 id='dependency-resolution-task-scheduling-circular-dependencies'>