From d2faad3ff31f0fab0cf280c05ee333992f7a7d27 Mon Sep 17 00:00:00 2001
From: Martyn Welch <martyn.welch@collabora.com>
Date: Wed, 9 Oct 2024 14:15:38 +0100
Subject: boot: pxe_utils: Add fallback support

When configured correctly, we can detect when boot fails after the boot
process has been handed over to the kernel through the use of U-Boot's
bootcount support. In some instances, such as when we are performing
atomic updates via a system such as OSTree, it is desirable to provide a
fallback option so that we can return to a previous (hopefully working)
state.

Add a "fallback" option to the supported extlinux configuration options
that points to a label like "default" so that we can utilise this in
later commits.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---
 doc/README.pxe | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'doc')

diff --git a/doc/README.pxe b/doc/README.pxe
index 172201093d0..af2e64a5776 100644
--- a/doc/README.pxe
+++ b/doc/README.pxe
@@ -120,6 +120,11 @@ Unrecognized commands are ignored.
 default <label>	    - the label named here is treated as the default and is
 		      the first label 'pxe boot' attempts to boot.
 
+fallback <label>    - the label named here is treated as a fallback option that
+		      may be attempted should it be detected that booting of
+		      the default has failed to complete, for example via
+		      U-Boot's boot count limit functionality.
+
 menu title <string> - sets a title for the menu of labels being displayed.
 
 menu include <path> - use tftp to retrieve the pxe file at <path>, which
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