diff --git a/IOMMU.md b/IOMMU.md
new file mode 100644
index 0000000..472b052
--- /dev/null
+++ b/IOMMU.md
@@ -0,0 +1 @@
+Starts at S2 IO offset 0x9000. Seems to have 4095 consecutive registers, where each register maps a 4K page.
\ No newline at end of file