Add information about downloading compcert

1 files changed, 14 insertions, 0 deletions

diff --git a/README.md b/README.md
index 5c1d8a0..71052f7 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,20 @@ To build the project on OSX, currently the makefile has to be manually edited so
 sed -i'' 's/x86_64-linux/x86_64-macosx/' Makefile
 ```
 
+### Downloading CompCert
+
+CompCert is added as a submodule in the `lib/CompCert` directory. It is needed to run the build process below, as it is the one dependency that is not downloaded by nix, and has to be downloaded together with the repository. To clone CompCert together with this project, you can run:
+
+``` shell
+git clone --recursive https://github.com/ymherklotz/coqup
+```
+
+If the repository is already cloned, you can run the following command to make sure that CompCert is also downloaded:
+
+``` shell
+git submodule update --init
+```
+
 ### Setting up Nix
 
 Nix is a package manager that can create an isolated environment so that the builds are reproducible. Once nix is installed, it can be used in the following way.