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.we...@collabora.com>
---
boot/pxe_utils.c | 15 +++++++++++++++
doc/README.pxe | 5 +++++
include/pxe_utils.h | 2 ++
3 files changed, 22 insertions(+)
diff --git a/boot/pxe_utils.c b/boot/pxe_utils.c
index 4e27842b08..a80119c9a3 100644
--- a/boot/pxe_utils.c
+++ b/boot/pxe_utils.c
@@ -781,6 +781,7 @@ enum token_type {
T_IPAPPEND,
T_BACKGROUND,
T_KASLRSEED,
+ T_FALLBACK,
T_INVALID
};
@@ -814,6 +815,7 @@ static const struct token keywords[] = {
{"ipappend", T_IPAPPEND,},
{"background", T_BACKGROUND,},
{"kaslrseed", T_KASLRSEED,},
+ {"fallback", T_FALLBACK,},
{NULL, T_INVALID}
};
@@ -1356,6 +1358,18 @@ static int parse_pxefile_top(struct pxe_context *ctx,
char *p, unsigned long bas
break;
+ case T_FALLBACK:
+ err = parse_sliteral(&p, &label_name);
+
+ if (label_name) {
+ if (cfg->fallback_label)
+ free(cfg->fallback_label);
+
+ cfg->fallback_label = label_name;
+ }
+
+ break;
+
case T_INCLUDE:
err = handle_include(ctx, &p,
base + ALIGN(strlen(b), 4), cfg,
@@ -1395,6 +1409,7 @@ void destroy_pxe_menu(struct pxe_menu *cfg)
free(cfg->title);
free(cfg->default_label);
+ free(cfg->fallback_label);
list_for_each_safe(pos, n, &cfg->labels) {
label = list_entry(pos, struct pxe_label, list);
diff --git a/doc/README.pxe b/doc/README.pxe
index 172201093d..af2e64a577 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
diff --git a/include/pxe_utils.h b/include/pxe_utils.h
index 9f19593048..a408fb7f13 100644
--- a/include/pxe_utils.h
+++ b/include/pxe_utils.h
@@ -62,6 +62,7 @@ struct pxe_label {
*
* title - the name of the menu as given by a 'menu title' line.
* default_label - the name of the default label, if any.
+ * fallback_label - the name of the fallback label, if any.
* bmp - the bmp file name which is displayed in background
* timeout - time in tenths of a second to wait for a user key-press before
* booting the default label.
@@ -73,6 +74,7 @@ struct pxe_label {
struct pxe_menu {
char *title;
char *default_label;
+ char *fallback_label;
char *bmp;
int timeout;
int prompt;
--
2.45.2
