Move kernel sources to platform specific subdirs
diff --git a/etc/platforms/platforms.jmk b/etc/platforms/platforms.jmk
new file mode 100644
index 0000000..f4bac15
--- /dev/null
+++ b/etc/platforms/platforms.jmk
@@ -0,0 +1,7 @@
+# -*- tcl -*-
+
+isa x86_32
+device pc-generic x86_32
+
+isa riscv32
+device esp32c3 riscv32