README: document dependency on kernel crypto/hash API (#5457)

The hmac and sha256 algorithms are used in sd-id128.

Closes: https://github.com/systemd/systemd/issues/5454
Closes: https://github.com/systemd/systemd/issues/5455

1 files changed, 5 insertions, 0 deletions

diff --git a/README b/README
index ac8620c75b..a4a6493959 100644
--- a/README
+++ b/README
@@ -50,6 +50,11 @@ REQUIREMENTS:
           CONFIG_PROC_FS
           CONFIG_FHANDLE (libudev, mount and bind mount handling)
 
+        Kernel crypto/hash API
+          CONFIG_CRYPTO_USER_API_HASH
+          CONFIG_CRYPTO_HMAC
+          CONFIG_CRYPTO_SHA256
+
         udev will fail to work with the legacy sysfs layout:
           CONFIG_SYSFS_DEPRECATED=n