Following up from #5593 (comment): To make sure I verify an observation with a fresh genode repository that doesn't contain any build artifacts from previous builds, I used the following steps:

$ cd /home/user/misc-code
$ git clone git@github.com:genodelabs/genode.git
$ cd genode
$ git checkout staging
$ tool/create_builddir x86_64 build/x86_64-staging

Unfortunately, I had the environment variable GENODE_DIR set to /home/user/code/genode which hosts our genode fork (notice code vs misc-code. This meant that the build/x86_64-staging/Makefile was pointing to the other genode directory:

$ pwd
/home/user/misc-code/genode
$ ls -hal build/x86_64-staging
total 12K
drwxrwxr-x 3 user user 4.0K Oct 23 13:37 .
drwxrwxr-x 3 user user 4.0K Oct 23 13:37 ..
drwxrwxr-x 2 user user 4.0K Oct 23 13:37 etc
lrwxrwxrwx 1 user user   45 Oct 23 13:37 Makefile -> /home/user/code/genode/tool/builddir/build.mk

While create_builddir did produce some warnings, everything seemed good enough.

When executing a run-script using make -C build/x86_64-staging/ KERNEL=hw BOARD=pc run/depot_download it ended up building from our genode fork instead of the current genode (staging) directory.

This led me wondering, would it make sense to set GENODE_DIR unconditionally in tool/create_builddir?

diff --git a/tool/create_builddir b/tool/create_builddir
index d78c9c0375..ce646864b8 100755
--- a/tool/create_builddir
+++ b/tool/create_builddir
@@ -34,7 +34,7 @@ usage:
 # Determine Genode base directory based on the known location of the
 # 'create_builddir' tool within the Genode source tree
 #
-GENODE_DIR ?= $(realpath $(dir $(MAKEFILE_LIST))/..)
+GENODE_DIR := $(realpath $(dir $(MAKEFILE_LIST))/..)
 
 #
 # Define default location of the build directory if not explicitly specified

In any case, please consider this as a minor nitpick and feel free to close this issue without comment if it breaks a use case that I'm unaware of.