building/hadrian/quick-start.md

@@ -121,3 +121,15 @@ The equivalent of `mk/build.mk` in the make build system is the `hadrian/src/Use
 
 
 Hadrian has an entire document dedicated to this topic, with various examples. You can find it [ here](https://github.com/snowleopard/hadrian/blob/master/doc/user-settings.md).
+
+## Updating Hadrian
+
+
+Hadrian is a submodule of the main GHC git repository, located at the root of the source tree, at path `hadrian/`. This submodule tracks `https://git.haskell.org/hadrian.git`, but the repository where Hadrian development actually takes place is on github, at `https://github.com/snowleopard/hadrian.git`. The former is manually updated with new commits from the latter every now and then, which means you occasionally might need to point `hadrian/` to the github repository's `master` branch to get some fixes or new features. This can be done as follows:
+
+```
+# move to the root of your ghc source tree, then:
+$ cd hadrian
+$ git remote add snowleopard https://github.com/snowleopard/hadrian.git
+$ git fetch snowleopard && git checkout snowleopard/master
+```
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