diff --git a/data.hpp b/data.hpp
new file mode 100644
index 0000000..6ef8911
--- /dev/null
+++ b/data.hpp
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <cstdint>
+
+namespace ipmi_flash
+{
+
+struct ExtChunkHdr
+{
+    std::uint32_t length; /* Length of the data queued (little endian). */
+} __attribute__((packed));
+
+/** P2A configuration response. */
+struct PciConfigResponse
+{
+    std::uint32_t address;
+} __attribute__((packed));
+
+} // namespace ipmi_flash