downgrade linux: Buildroot patching

Author: cirosantilli

README.adoc

@@ -4128,6 +4128,15 @@ We don't expect those changes to be very difficult. A good way to approach the t
 
 Then, if you spot an option that is wrong, some grepping in this repo should quickly point you to the code you need to modify.
 
+It also possible that you will need to apply some patches from newer Buildroot versions for it to build, due to incompatibilities with the host Ubuntu packages and that Buildroot version. Just read the error message, and try:
+
+* `git log master -- packages/<pkg>`
+* Google the error message for mailing list hits
+
+Successful port reports:
+
+* v3.18: https://github.com/cirosantilli/linux-kernel-module-cheat/issues/39#issuecomment-438525481
+
 === Kernel command line parameters
 
 Bootloaders can pass a string as input to the Linux kernel when it is booting to control its behaviour, much like the `execve` system call does to userland processes.