test/README.testsuite: add section for Ubuntu CI blacklist files

Add some docs explaining how blacklist individual test/TEST-*
tests in Ubuntu CI using per-test blacklist files.

diff --git a/test/README.testsuite b/test/README.testsuite
index 2753ed6e3a6e64f0c36c172a63508bdfffd07ecc..9e0c36512c953d4bcfa0621230416519d76b086c 100644 (file)
--- a/test/README.testsuite
+++ b/test/README.testsuite
@@ -97,3 +97,26 @@ kernel command line parameter with $KERNEL_APPEND and then log in as root.
 $ sudo make -C test/TEST-01-BASIC KERNEL_APPEND="systemd.unit=multi-user.target" run
 
 Root password is empty.
+
+Ubuntu CI
+=========
+
+New PR submitted to the project are run through regression tests, and one set
+of those is the 'autopkgtest' runs for several different architectures, called
+'Ubuntu CI'.  Part of that testing is to run all these tests.  Sometimes these
+tests are temporarily blacklisted from running in the 'autopkgtest' tests while
+debugging a flaky test; that is done by creating a file in the test directory
+named 'blacklist-ubuntu-ci', for example to prevent the TEST-01-BASIC test from
+running in the 'autopkgtest' runs, create the file
+'TEST-01-BASIC/blacklist-ubuntu-ci'.
+
+The tests may be disabled only for specific archs, by creating a blacklist file
+with the arch name at the end, e.g.
+'TEST-01-BASIC/blacklist-ubuntu-ci-arm64' to disable the TEST-01-BASIC test
+only on test runs for the 'arm64' architecture.
+
+Note the arch naming is not from 'uname -m', it is Debian arch names:
+https://wiki.debian.org/ArchitectureSpecificsMemo
+
+For PRs that fix a currently blacklisted test, the PR should include removal
+of the blacklist file.