[PATCH blktests v3 3/3] doc: document how to configure bcache tests

Add a bcache entry in running-tests which explains how to configure
blktests for the bcache tests.

Signed-off-by: Daniel Wagner <[email protected]>
---
 Documentation/running-tests.md | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/running-tests.md b/Documentation/running-tests.md
index f9da042bb3a0..c4abc6767cd0 100644
--- a/Documentation/running-tests.md
+++ b/Documentation/running-tests.md
@@ -189,6 +189,22 @@ THROTL_BLKDEV_TYPES="sdebug" ./check throtl/
 THROTL_BLKDEV_TYPES="nullb sdebug" ./check throtl/
 ```
 
+### bcache test configuration
+
+The bcache tests require multiple devices to run simultaneously. By default,
+blktests executes each test case iteratively for every individual device listed
+in TEST_DEVS. This standard behavior makes it impossible to pass a group of
+devices into a single test via TEST_DEVS.
+
+To solve this, the TEST_CASE_DEV_ARRAY was introduced. This allows for custom
+device configurations on a per-test basis. For bcache tests, a minimum of three
+devices is required. Configuration Example
+
+Add the following to your configuration to define the devices used for all
+bcache tests:
+
+TEST_CASE_DEV_ARRAY[bcache/*]="/dev/nvme0n1 /dev/vdb /dev/vdc"
+
 ### Normal user
 
 To run test cases which require normal user privilege, prepare a user and

-- 
2.52.0