1 files changed, 133 insertions, 0 deletions
diff --git a/Documentation/merge-strategies.txt b/Documentation/merge-strategies.txt
new file mode 100644
index 0000000000..fd5d748d1b
--- /dev/null
+++ b/Documentation/merge-strategies.txt
@@ -0,0 +1,133 @@
+MERGE STRATEGIES
+----------------
+
+The merge mechanism (`git merge` and `git pull` commands) allows the
+backend 'merge strategies' to be chosen with `-s` option.  Some strategies
+can also take their own options, which can be passed by giving `-X<option>`
+arguments to `git merge` and/or `git pull`.
+
+resolve::
+	This can only resolve two heads (i.e. the current branch
+	and another branch you pulled from) using a 3-way merge
+	algorithm.  It tries to carefully detect criss-cross
+	merge ambiguities and is considered generally safe and
+	fast.
+
+recursive::
+	This can only resolve two heads using a 3-way merge
+	algorithm.  When there is more than one common
+	ancestor that can be used for 3-way merge, it creates a
+	merged tree of the common ancestors and uses that as
+	the reference tree for the 3-way merge.  This has been
+	reported to result in fewer merge conflicts without
+	causing mismerges by tests done on actual merge commits
+	taken from Linux 2.6 kernel development history.
+	Additionally this can detect and handle merges involving
+	renames.  This is the default merge strategy when
+	pulling or merging one branch.
++
+The 'recursive' strategy can take the following options:
+
+ours;;
+	This option forces conflicting hunks to be auto-resolved cleanly by
+	favoring 'our' version.  Changes from the other tree that do not
+	conflict with our side are reflected to the merge result.
+	For a binary file, the entire contents are taken from our side.
++
+This should not be confused with the 'ours' merge strategy, which does not
+even look at what the other tree contains at all.  It discards everything
+the other tree did, declaring 'our' history contains all that happened in it.
+
+theirs;;
+	This is the opposite of 'ours'; note that, unlike 'ours', there is
+	no 'theirs' merge stragegy to confuse this merge option with.
+
+patience;;
+	With this option, 'merge-recursive' spends a little extra time
+	to avoid mismerges that sometimes occur due to unimportant
+	matching lines (e.g., braces from distinct functions).  Use
+	this when the branches to be merged have diverged wildly.
+	See also linkgit:git-diff[1] `--patience`.
+
+diff-algorithm=[patience|minimal|histogram|myers];;
+	Tells 'merge-recursive' to use a different diff algorithm, which
+	can help avoid mismerges that occur due to unimportant matching
+	lines (such as braces from distinct functions).  See also
+	linkgit:git-diff[1] `--diff-algorithm`.
+
+ignore-space-change;;
+ignore-all-space;;
+ignore-space-at-eol;;
+ignore-cr-at-eol;;
+	Treats lines with the indicated type of whitespace change as
+	unchanged for the sake of a three-way merge.  Whitespace
+	changes mixed with other changes to a line are not ignored.
+	See also linkgit:git-diff[1] `-b`, `-w`,
+	`--ignore-space-at-eol`, and `--ignore-cr-at-eol`.
++
+* If 'their' version only introduces whitespace changes to a line,
+  'our' version is used;
+* If 'our' version introduces whitespace changes but 'their'
+  version includes a substantial change, 'their' version is used;
+* Otherwise, the merge proceeds in the usual way.
+
+renormalize;;
+	This runs a virtual check-out and check-in of all three stages
+	of a file when resolving a three-way merge.  This option is
+	meant to be used when merging branches with different clean
+	filters or end-of-line normalization rules.  See "Merging
+	branches with differing checkin/checkout attributes" in
+	linkgit:gitattributes[5] for details.
+
+no-renormalize;;
+	Disables the `renormalize` option.  This overrides the
+	`merge.renormalize` configuration variable.
+
+no-renames;;
+	Turn off rename detection.
+	See also linkgit:git-diff[1] `--no-renames`.
+
+find-renames[=<n>];;
+	Turn on rename detection, optionally setting the similarity
+	threshold.  This is the default.
+	See also linkgit:git-diff[1] `--find-renames`.
+
+rename-threshold=<n>;;
+	Deprecated synonym for `find-renames=<n>`.
+
+subtree[=<path>];;
+	This option is a more advanced form of 'subtree' strategy, where
+	the strategy makes a guess on how two trees must be shifted to
+	match with each other when merging.  Instead, the specified path
+	is prefixed (or stripped from the beginning) to make the shape of
+	two trees to match.
+
+octopus::
+	This resolves cases with more than two heads, but refuses to do
+	a complex merge that needs manual resolution.  It is
+	primarily meant to be used for bundling topic branch
+	heads together.  This is the default merge strategy when
+	pulling or merging more than one branch.
+
+ours::
+	This resolves any number of heads, but the resulting tree of the
+	merge is always that of the current branch head, effectively
+	ignoring all changes from all other branches.  It is meant to
+	be used to supersede old development history of side
+	branches.  Note that this is different from the -Xours option to
+	the 'recursive' merge strategy.
+
+subtree::
+	This is a modified recursive strategy. When merging trees A and
+	B, if B corresponds to a subtree of A, B is first adjusted to
+	match the tree structure of A, instead of reading the trees at
+	the same level. This adjustment is also done to the common
+	ancestor tree.
+
+With the strategies that use 3-way merge (including the default, 'recursive'),
+if a change is made on both branches, but later reverted on one of the
+branches, that change will be present in the merged result; some people find
+this behavior confusing.  It occurs because only the heads and the merge base
+are considered when performing a merge, not the individual commits.  The merge
+algorithm therefore considers the reverted change as no change at all, and
+substitutes the changed version instead.