Since commit 7f1cc5dd869d ("defaultenv: add base and external defaultenv
in pure_initcall"), the environment given with
CONFIG_DEFAULT_ENVIRONMENT_PATH is added before boards add their own
overlays with defaultenv_append_directory(). As overlays are applied in
the order they were added, board overlays now overwrite the external
environment, contrary to Documentation/user/defaultenv-2.rst, and BSPs
can no longer replace a board's default environment files, e.g. its boot
scripts.
Restore the documented order by giving each overlay a priority and
keeping the list sorted by it: the base and board specific overlays are
applied first, followed by CONFIG_DEFAULT_ENVIRONMENT_PATH. Overlays
added at runtime with defaultenv_append_runtime_directory(), like the
QEMU fw_cfg environment, are still applied last, so they keep
overwriting the external environment.
No in-tree board adds its own overlay and sets
CONFIG_DEFAULT_ENVIRONMENT_PATH at the same time, so only out-of-tree
configurations are affected. Add a migration guide entry for them.
Fixes: 7f1cc5dd869d ("defaultenv: add base and external defaultenv in
pure_initcall")
Reported-by: Primoz Fiser <[email protected]>
Signed-off-by: Florijan Plohl <[email protected]>
---
RFC:
https://lore.barebox.org/barebox/[email protected]/
Changes since RFC, following Ahmad's review:
- Fix the order generically in defaultenv.c instead of a per-board
opt-in
- Keep runtime overlays like QEMU fw_cfg after the external
environment
- Add a migration guide entry
- Drop the phytec-som-imx6 board patch
Priorities are used, as appending the external environment from
defaultenv_load() would put it after fw_cfg again, and a later initcall
would depend on link and probe order.
Tested in sandbox (external overrides board, /env unchanged without
it, runtime overlay still wins) and on a phyCORE-i.MX6 with the Yocto
BSP environment, not with a real QEMU fw_cfg.
.../migration-guides/migration-master.rst | 15 ++++
Documentation/user/defaultenv-2.rst | 5 ++
defaultenv/defaultenv.c | 82 ++++++++++++++++---
3 files changed, 89 insertions(+), 13 deletions(-)
diff --git a/Documentation/migration-guides/migration-master.rst
b/Documentation/migration-guides/migration-master.rst
index 715edd5934..59b9514997 100644
--- a/Documentation/migration-guides/migration-master.rst
+++ b/Documentation/migration-guides/migration-master.rst
@@ -20,3 +20,18 @@ points at a FIT.
Existing users, if any, will fail-secure: The command will now exit with a
failure::
bootm: invalid option -- s
+
+Default environment overlay order
+---------------------------------
+
+Releases since v2026.01.0 applied board specific default environment overlays
+added with ``defaultenv_append_directory()`` after the environment given
+with ``CONFIG_DEFAULT_ENVIRONMENT_PATH`` and thus overwrote its files.
+
+The documented order has been restored: ``CONFIG_DEFAULT_ENVIRONMENT_PATH``
+is applied after the board specific overlays again and can overwrite their
+files. Overlays only available at runtime, like an environment passed via
+QEMU fw_cfg, are still applied last.
+
+BSPs that started to rely on the board specific overlay taking precedence
+need to remove the conflicting files from their external environment.
diff --git a/Documentation/user/defaultenv-2.rst
b/Documentation/user/defaultenv-2.rst
index 719abe2782..78adb69293 100644
--- a/Documentation/user/defaultenv-2.rst
+++ b/Documentation/user/defaultenv-2.rst
@@ -34,6 +34,11 @@ board specific overlay, or overlays, could be at any path,
but usually follows
the form given. They must be added to a Makefile in ``bbenv-y`` and
``defaultenv_append_directory()`` used to add them in board init code.
+Overlays that are only available at runtime, like an environment passed
+via QEMU fw_cfg as ``opt/org.barebox.env``, are applied after all of the
+above and can thus also overwrite files from
+``$(CONFIG_DEFAULT_ENVIRONMENT_PATH)``.
+
Note that not all of the above directories will necessarily be
included in your default environment, it depends on your barebox
configuration settings. You can see the configuration variables
diff --git a/defaultenv/defaultenv.c b/defaultenv/defaultenv.c
index 573b1f862f..9a7600a7f9 100644
--- a/defaultenv/defaultenv.c
+++ b/defaultenv/defaultenv.c
@@ -24,14 +24,63 @@
static LIST_HEAD(defaultenv_list);
+/*
+ * defaultenv_list is kept sorted by ascending priority, overlays of the same
+ * priority stay in the order they were added. defaultenv_load() applies them
+ * in list order, so a file from a later overlay replaces the same file of an
+ * earlier one, unless ENV_FLAG_NO_OVERWRITE is passed.
+ */
+enum defaultenv_prio {
+ /* base and board specific overlays, added with defaultenv_append() */
+ DEFAULTENV_PRIO_BOARD,
+ /* the environment given with CONFIG_DEFAULT_ENVIRONMENT_PATH */
+ DEFAULTENV_PRIO_EXTERNAL,
+ /* overlays added with defaultenv_append_runtime_directory() */
+ DEFAULTENV_PRIO_RUNTIME,
+};
+
struct defaultenv {
struct list_head list;
+ enum defaultenv_prio prio;
const char *srcdir;
const char *name;
void *buf;
size_t size;
};
+static void defaultenv_add(struct defaultenv *df)
+{
+ struct defaultenv *pos;
+
+ /*
+ * Insert behind all entries of the same priority. list_add_sort()
+ * would insert in front of them and thus reverse the order in which
+ * overlays of the same priority were added.
+ */
+ list_for_each_entry(pos, &defaultenv_list, list) {
+ if (pos->prio > df->prio) {
+ list_add_tail(&df->list, &pos->list);
+ return;
+ }
+ }
+
+ list_add_tail(&df->list, &defaultenv_list);
+}
+
+static void __defaultenv_append(void *buf, unsigned int size, const char *name,
+ enum defaultenv_prio prio)
+{
+ struct defaultenv *df;
+
+ df = xzalloc(sizeof(*df));
+ df->buf = buf;
+ df->size = size;
+ df->name = name;
+ df->prio = prio;
+
+ defaultenv_add(df);
+}
+
/*
* defaultenv_append - append a envfs buffer to the default environment
* @buf: The buffer containing the binary environment. If it is
@@ -39,20 +88,24 @@ struct defaultenv {
* @size: The length of the buffer
*
* This adds an overlay to the default environment. New files will be created,
- * existing files will be overwritten with the overlay.
+ * existing files will be overwritten with the overlay. The environment given
+ * with CONFIG_DEFAULT_ENVIRONMENT_PATH is applied after all overlays added
+ * with this function and can thus overwrite their files.
*/
void defaultenv_append(void *buf, unsigned int size, const char *name)
{
- struct defaultenv *df;
-
- df = xzalloc(sizeof(*df));
- df->buf = buf;
- df->size = size;
- df->name = name;
-
- list_add_tail(&df->list, &defaultenv_list);
+ __defaultenv_append(buf, size, name, DEFAULTENV_PRIO_BOARD);
}
+/*
+ * defaultenv_append_runtime_directory - append a directory to the default
+ * environment
+ * @srcdir: The directory whose contents should be added
+ *
+ * This adds an overlay that is copied from @srcdir when the default
environment
+ * is loaded. It is applied after the environment given with
+ * CONFIG_DEFAULT_ENVIRONMENT_PATH and can thus overwrite its files.
+ */
void defaultenv_append_runtime_directory(const char *srcdir)
{
struct defaultenv *df;
@@ -60,8 +113,9 @@ void defaultenv_append_runtime_directory(const char *srcdir)
df = xzalloc(sizeof(*df));
df->srcdir = srcdir;
df->name = srcdir;
+ df->prio = DEFAULTENV_PRIO_RUNTIME;
- list_add_tail(&df->list, &defaultenv_list);
+ defaultenv_add(df);
}
static int defaultenv_load_one(struct defaultenv *df, const char *dir,
@@ -158,10 +212,12 @@ static int defaultenv_init(void)
/*
* The traditional or external environment given with
- * CONFIG_DEFAULT_ENVIRONMENT_PATH.
+ * CONFIG_DEFAULT_ENVIRONMENT_PATH. It is added here already, but
+ * still applied after the board specific overlays added later on.
*/
- defaultenv_append((void *)default_environment,
- default_environment_size, "defaultenv");
+ __defaultenv_append((void *)default_environment,
+ default_environment_size, "defaultenv",
+ DEFAULTENV_PRIO_EXTERNAL);
return 0;
}
--
2.43.0
