diff --git a/documentation/asciidoc/computers/config_txt/boot.adoc b/documentation/asciidoc/computers/config_txt/boot.adoc
index 1fcea1b25..469793326 100644
--- a/documentation/asciidoc/computers/config_txt/boot.adoc
+++ b/documentation/asciidoc/computers/config_txt/boot.adoc
@@ -163,6 +163,11 @@ Specifies a subdirectory/prefix from which to load overlays - defaults to `overl
 
 NOTE: Unless `+${os_prefix}${overlay_prefix}README+` exists, overlays are shared with the main OS (i.e. `os_prefix` is ignored).
 
+[[sha256]]
+=== `sha256`
+
+If set to non-zero, enables the logging of SHA256 hashes for loaded files (the kernel, initramfs, Device Tree .dtb file and overlays), as generated by the `sha256sum` utility. The logging output goes to the UART if enabled, and is also accessible via `sudo vcdbg log msg`. This option may be useful when debugging booting problems, but at the cost of potentially adding _many_ seconds to the boot time. Defaults to 0 on all platforms.
+
 === `uart_2ndstage`
 
 Setting `uart_2ndstage=1` causes the second-stage loader (`bootcode.bin` on devices prior to the Raspberry Pi 4, or the boot code in the  EEPROM for Raspberry Pi 4 devices) and the main firmware (`start*.elf`) to output diagnostic information to UART0.