tests: Document them in README.source

debian/README.source

@@ -78,3 +78,26 @@ TODO:
 - How to define a flavour
 - More detail on generation of debian/control and configs
 
+Running tests
+=============
+
+linux supports autopkgtest and should be able to run most of the
+kernel's self-tests on any architecture where kexec is supported,
+but it has higher resource requirements than most packages:
+
+- A VM with plenty of disk space (10GB is enough), RAM (1GB is
+  probably enough) and at least 2 CPUs
+- The temporary directory for adt-virt-qemu (-o option) will need
+  several GB of space, so a tmpfs may not be suitable
+
+Note that if you tell adt-run to use an 'unbuilt tree' (i.e. an
+unpacked source package) it does not exclude VCS directories such as
+.git.  Either use a packed source package or copy the working tree
+elsewhere excluding .git.
+
+Example invocation:
+
+    adt-run -B ../linux-image-4.2.0-rc6-amd64_4.2~rc6-1~exp2_amd64.deb \
+        ../linux_4.2~rc6-1~exp2.dsc \
+	--timeout-test=1200 \
+        --- adt-virt-qemu /var/cache/autopkgtest/adt-sid.img -o /var/tmp -c 2