diff --git a/documentation/asciidoc/computers/config_txt/boot.adoc b/documentation/asciidoc/computers/config_txt/boot.adoc
index acdd553f1..786df5f5c 100644
--- a/documentation/asciidoc/computers/config_txt/boot.adoc
+++ b/documentation/asciidoc/computers/config_txt/boot.adoc
@@ -165,6 +165,8 @@ Default: `0x0`
 [[enable_rp1_uart]]
 ==== `enable_rp1_uart`
 
+Raspberry Pi 5 only.
+
 When set to `1`, firmware initialises RP1 UART0 to 115200bps and doesn't reset RP1 before starting the OS (separately configurable using `pciex4_reset=1`).
 This makes it easier to get UART output on the 40-pin header in early boot-code, for instance during bare-metal debug.