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+# Protobuf packaging
+
+This directory contains Bazel rules for building packaging and distribution
+artifacts.
+
+*Everything in this directory should be considered internal and subject to
+change.*
+
+## Protocol compiler binary packaging
+
+The protocol compiler is used in binary form in various places. There are rules
+which package it, along with commonly used `.proto` files, for distribution.
+
+## Source distribution packaging
+
+Protobuf releases include source distributions, sliced by target language (C++,
+Java, etc.). There are rules in this package to define those source archives.
+These depend upon `pkg_files` rules elsewhere in the repo to get the contents.
+
+The source distribution files should include the outputs from `autogen.sh`, but
+this isn't something we can reliably do from Bazel. To produce fully functioning
+source distributions, run `autogen.sh` before building the archives (this
+populates the necessary files directly into the source tree).
+
+## C++ runtime binary distribution
+
+The `cc_dist_library` rule creates composite libraries from several other
+`cc_library` targets. Bazel uses a "fine-grained" library model, where each
+`cc_library` produces its own library artifacts, without transitive
+dependencies. The `cc_dist_library` rule combines several other libraries
+together, creating a single library that may be suitable for distribution.