diff --git a/firmware/release-notes.md b/firmware/release-notes.md
index 548b0c8e..c9f41e72 100644
--- a/firmware/release-notes.md
+++ b/firmware/release-notes.md
@@ -7,6 +7,10 @@ https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#raspberry-
    * PCIe retry on error
    * NVMe logging changes
    * NVMe attempts to boot twice
+   * Increase the maximum GPU memory size from 256MB to 512MB so long as
+     boot_ramdisk=0. This should only be used with the legacy camera
+     application and FKMS for very memory intensive camera operations.
+     N.B. The new libcamera and KMS driver use CMA instead of GPU memory.
 
 ## 2021-12-02 - Promote the 2021-12-02 beta release to LATEST/STABLE
    * Just fixes a regression with MTB detection affecting factory testing