diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 000000000..e406bcfa5
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,12 @@
+[submodule "riscv-o3"]
+	path = riscv-o3
+	url = git@github.com:stineje/riscv-o3.git
+[submodule "sky130/sky130_osu_sc_t12"]
+	path = sky130/sky130_osu_sc_t12
+	url = https://foss-eda-tools.googlesource.com/skywater-pdk/libs/sky130_osu_sc_t12/
+[submodule "sky130/sky130_osu_sc_t15"]
+	path = sky130/sky130_osu_sc_t15
+	url = https://foss-eda-tools.googlesource.com/skywater-pdk/libs/sky130_osu_sc_t15/
+[submodule "sky130/sky130_osu_sc_t18"]
+	path = sky130/sky130_osu_sc_t18
+	url = https://foss-eda-tools.googlesource.com/skywater-pdk/libs/sky130_osu_sc_t18/
diff --git a/riscv-o3 b/riscv-o3
index afb27bd55..a13ac64fa 160000
--- a/riscv-o3
+++ b/riscv-o3
@@ -1 +1 @@
-Subproject commit afb27bd558a9b6fabb6b768ae81ef122b4db9eea
+Subproject commit a13ac64fa50c187ffd489cdb2f4a4a70e60fc837
diff --git a/sky130/sky130_osu_sc_t12 b/sky130/sky130_osu_sc_t12
new file mode 160000
index 000000000..87ca77795
--- /dev/null
+++ b/sky130/sky130_osu_sc_t12
@@ -0,0 +1 @@
+Subproject commit 87ca77795004bea5525b25badd7ec36cbc8222e1
diff --git a/sky130/sky130_osu_sc_t15 b/sky130/sky130_osu_sc_t15
new file mode 160000
index 000000000..dae3c2282
--- /dev/null
+++ b/sky130/sky130_osu_sc_t15
@@ -0,0 +1 @@
+Subproject commit dae3c2282e10d72f57af61d1dd73a1b0aead63f9
diff --git a/sky130/sky130_osu_sc_t18 b/sky130/sky130_osu_sc_t18
new file mode 160000
index 000000000..6c20402bf
--- /dev/null
+++ b/sky130/sky130_osu_sc_t18
@@ -0,0 +1 @@
+Subproject commit 6c20402bf853e6bf3985fce49fe88ca25502cc63