diff --git a/doc/guix.texi b/doc/guix.texi
index 969b722cc3..2cf5595329 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -42273,6 +42273,50 @@ the boot files and Guix System from a
 @acronym{TFTP, Trivial File Transfer Protocol} server, discovered via
 @acronym{DHCP, Dynamic Host Configuration Protocol}.
 
+@code{override} expects a procedure with @code{grub-configuration}
+argument and return value, when a GRUB bootloader is specified:
+
+@deftp {Data Type} grub-menu-entry
+Available @code{grub-menu-entry} fields are:
+@table @asis
+@item @code{label} (type: string)
+Entry label with e.g.  rank, kernel, and date.
+@item @code{device} (type: grub-device)
+Device UUID or label, NFS path, or block device path, with payload.
+@item @code{device-mount-point} (type: maybe-string)
+Remove prefix from relevant paths.
+@item @code{device-subvol} (type: maybe-string)
+Access files from this Btrfs subvolume.
+@item @code{directive} (type: directive-or-file-like)
+Configuration for a Linux or Multiboot directive, or a file for the
+chainloader directive.
+@deftp {Data Type} linux-directive
+Available @code{linux-directive} fields are:
+@table @asis
+@item @code{extra-initrd} (type: maybe-string)
+Path to out-of-store initrd with secrets.
+@item @code{initrd} (type: file-like)
+The initial RAM disk to use.
+@item @code{kernel} (type: file-like)
+The Linux kernel image to boot.
+@item @code{arguments} (type: string-list)
+The list of extra Linux kernel command-line arguments.
+@end table
+@end deftp
+@deftp {Data Type} multiboot-directive
+Available @code{multiboot-directive} fields are:
+@table @asis
+@item @code{kernel} (type: file-like)
+The Multiboot kernel image to boot.
+@item @code{arguments} (default: @code{()}) (type: string-list)
+The list of Multiboot kernel command-line arguments.
+@item @code{modules} (default: @code{()}) (type: file-like-list)
+The list of commands for loading Multiboot modules.
+@end table
+@end deftp
+@end table
+@end deftp
+
 @vindex extlinux-bootloader
 @item @code{extlinux-bootloader}
 Extlinux for "legacy" BIOS systems which use an MBR partition table.