[PATCH] EFI: update the documentation to correctly order loading SB keys

[luca.boccassi@gmail.com]

From: Luca Boccassi <bluca@debian.org>

Loading the PK locks down the EFI variables, so it needs to be done last.
Fix the order in the documentation and add a note.

Signed-off-by: Luca Boccassi <bluca@debian.org>
---
 doc/develop/uefi/uefi.rst | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst
index e0835beba4..68a0bb6832 100644
--- a/doc/develop/uefi/uefi.rst
+++ b/doc/develop/uefi/uefi.rst
@@ -169,12 +169,16 @@ Sign an image with one of the keys in "db" on your host
 
 Now in U-Boot install the keys on your board::
 
-    fatload mmc 0:1 <tmpaddr> PK.auth
-    setenv -e -nv -bs -rt -at -i <tmpaddr>:$filesize PK
-    fatload mmc 0:1 <tmpaddr> KEK.auth
-    setenv -e -nv -bs -rt -at -i <tmpaddr>:$filesize KEK
     fatload mmc 0:1 <tmpaddr> db.auth
     setenv -e -nv -bs -rt -at -i <tmpaddr>:$filesize db
+    fatload mmc 0:1 <tmpaddr> KEK.auth
+    setenv -e -nv -bs -rt -at -i <tmpaddr>:$filesize KEK
+    fatload mmc 0:1 <tmpaddr> PK.auth
+    setenv -e -nv -bs -rt -at -i <tmpaddr>:$filesize PK
+
+Note that loading a key into PK automatically enables Secure Boot, and further
+unsigned updates of secure EFI variables will no longer be allowed, so PK should
+be loaded last.
 
 Set up boot parameters on your board::
 
-- 
2.34.1