[PATCH 1/2] globalvar: propagate dev_set_param return value from globalvar_set

[PATCH 1/2] globalvar: propagate dev_set_param return value from globalvar_set

[Ahmad Fatoum]

dev_set_param() already returns an error code, which can be useful
for non-simple globalvars. Propagate it out of globalvar_set as well.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 common/globalvar.c  | 4 ++--
 include/globalvar.h | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/common/globalvar.c b/common/globalvar.c
index 876379b2538e..c2b0d5b4bbad 100644
--- a/common/globalvar.c
+++ b/common/globalvar.c
@@ -456,9 +456,9 @@ void globalvar_set_match(const char *match, const char *val)
 	}
 }
 
-void globalvar_set(const char *name, const char *val)
+int globalvar_set(const char *name, const char *val)
 {
-	dev_set_param(&global_device, name, val);
+	return dev_set_param(&global_device, name, val);
 }
 
 static int globalvar_simple_set(struct bobject *bobj, struct param_d *p,
diff --git a/include/globalvar.h b/include/globalvar.h
index e369616c632a..413cf72002a0 100644
--- a/include/globalvar.h
+++ b/include/globalvar.h
@@ -22,7 +22,7 @@ int globalvar_add_simple(const char *name, const char *value);
 void globalvar_remove(const char *name);
 char *globalvar_get_match(const char *match, const char *separator);
 void globalvar_set_match(const char *match, const char *val);
-void globalvar_set(const char *name, const char *val);
+int globalvar_set(const char *name, const char *val);
 
 int globalvar_add_simple_string(const char *name, char **value);
 int globalvar_add_simple_int(const char *name, int *value,
@@ -124,7 +124,7 @@ static inline char *globalvar_get_match(const char *match, const char *separator
 
 static inline void globalvar_set_match(const char *match, const char *val) {}
 
-static inline void globalvar_set(const char *name, const char *val) {}
+static inline int globalvar_set(const char *name, const char *val) { return 0; }
 
 static inline int nvvar_load(void)
 {
-- 
2.47.3

[PATCH 2/2] globalvar: add helpers for stashing global variables

[Ahmad Fatoum]

Configuring a FIT image boot with overlays involves setting not only
global.bootm.* variables, but also global.of.overlay.* variables.

For use in custom boot entry functions, provide functions for stashing
and restoring a set of variables. This allows dry run and boot fallback
behavior to not affect later boot attempts.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 common/globalvar.c  | 77 +++++++++++++++++++++++++++++++++++++++++++++
 include/globalvar.h |  3 ++
 2 files changed, 80 insertions(+)

diff --git a/common/globalvar.c b/common/globalvar.c
index c2b0d5b4bbad..e168d6055347 100644
--- a/common/globalvar.c
+++ b/common/globalvar.c
@@ -461,6 +461,83 @@ int globalvar_set(const char *name, const char *val)
 	return dev_set_param(&global_device, name, val);
 }
 
+struct globalvar_stashed {
+	const char *key;
+	const char *value;
+	struct list_head list;
+};
+
+static void globalvar_stashed_free(struct globalvar_stashed *elem)
+{
+	list_del(&elem->list);
+	free_const(elem->key);
+	free_const(elem->value);
+	free(elem);
+}
+
+int globalvar_stash_push(struct list_head *stash, ...)
+{
+	struct globalvar_stashed *elem, *safe;
+	const char *name;
+	int ret = -ENOMEM;
+	va_list args;
+	LIST_HEAD(tmp);
+
+	va_start(args, stash);
+
+	while ((name = va_arg(args, const char *))) {
+		const char *value;
+
+		elem = calloc(1, sizeof(*elem));
+		if (!elem)
+			goto out;
+
+		list_add_tail(&elem->list, &tmp);
+
+		elem->key = strdup_const(name);
+		if (!elem->key)
+			goto out;
+
+		value = globalvar_get(name);
+		if (!value) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		elem->value = strdup_const(value);
+		if (!elem->value)
+			goto out;
+	}
+
+	list_splice_tail(&tmp, stash);
+
+	ret = 0;
+out:
+	va_end(args);
+
+	if (ret) {
+		list_for_each_entry_safe(elem, safe, &tmp, list)
+			globalvar_stashed_free(elem);
+	}
+
+	return ret;
+}
+
+int globalvar_stash_pop(struct list_head *stash)
+{
+	struct globalvar_stashed *elem, *tmp;
+	int err = 0;
+
+	list_for_each_entry_safe(elem, tmp, stash, list) {
+		int ret = globalvar_set(elem->key, elem->value);
+		if (ret)
+			err = ret;
+		globalvar_stashed_free(elem);
+	}
+
+	return err;
+}
+
 static int globalvar_simple_set(struct bobject *bobj, struct param_d *p,
 				const char *val)
 {
diff --git a/include/globalvar.h b/include/globalvar.h
index 413cf72002a0..1d39849ddbab 100644
--- a/include/globalvar.h
+++ b/include/globalvar.h
@@ -24,6 +24,9 @@ char *globalvar_get_match(const char *match, const char *separator);
 void globalvar_set_match(const char *match, const char *val);
 int globalvar_set(const char *name, const char *val);
 
+int globalvar_stash_push(struct list_head *stash, ...) __attribute__((sentinel));
+int globalvar_stash_pop(struct list_head *stash);
+
 int globalvar_add_simple_string(const char *name, char **value);
 int globalvar_add_simple_int(const char *name, int *value,
 			     const char *format);
-- 
2.47.3

Re: [PATCH 2/2] globalvar: add helpers for stashing global variables

[Sascha Hauer]

On Thu, Mar 12, 2026 at 03:43:16PM +0100, Ahmad Fatoum wrote:
> Configuring a FIT image boot with overlays involves setting not only
> global.bootm.* variables, but also global.of.overlay.* variables.
> 
> For use in custom boot entry functions, provide functions for stashing
> and restoring a set of variables. This allows dry run and boot fallback
> behavior to not affect later boot attempts.

Looks generally good. I assume this is to replace the .dyn. type
variables, right?

Can we the a user before applying this?

Sascha

> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  common/globalvar.c  | 77 +++++++++++++++++++++++++++++++++++++++++++++
>  include/globalvar.h |  3 ++
>  2 files changed, 80 insertions(+)
> 
> diff --git a/common/globalvar.c b/common/globalvar.c
> index c2b0d5b4bbad..e168d6055347 100644
> --- a/common/globalvar.c
> +++ b/common/globalvar.c
> @@ -461,6 +461,83 @@ int globalvar_set(const char *name, const char *val)
>  	return dev_set_param(&global_device, name, val);
>  }
>  
> +struct globalvar_stashed {
> +	const char *key;
> +	const char *value;
> +	struct list_head list;
> +};
> +
> +static void globalvar_stashed_free(struct globalvar_stashed *elem)
> +{
> +	list_del(&elem->list);
> +	free_const(elem->key);
> +	free_const(elem->value);
> +	free(elem);
> +}
> +
> +int globalvar_stash_push(struct list_head *stash, ...)
> +{
> +	struct globalvar_stashed *elem, *safe;
> +	const char *name;
> +	int ret = -ENOMEM;
> +	va_list args;
> +	LIST_HEAD(tmp);
> +
> +	va_start(args, stash);
> +
> +	while ((name = va_arg(args, const char *))) {
> +		const char *value;
> +
> +		elem = calloc(1, sizeof(*elem));
> +		if (!elem)
> +			goto out;
> +
> +		list_add_tail(&elem->list, &tmp);
> +
> +		elem->key = strdup_const(name);
> +		if (!elem->key)
> +			goto out;
> +
> +		value = globalvar_get(name);
> +		if (!value) {
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
> +		elem->value = strdup_const(value);
> +		if (!elem->value)
> +			goto out;
> +	}
> +
> +	list_splice_tail(&tmp, stash);
> +
> +	ret = 0;
> +out:
> +	va_end(args);
> +
> +	if (ret) {
> +		list_for_each_entry_safe(elem, safe, &tmp, list)
> +			globalvar_stashed_free(elem);
> +	}
> +
> +	return ret;
> +}
> +
> +int globalvar_stash_pop(struct list_head *stash)
> +{
> +	struct globalvar_stashed *elem, *tmp;
> +	int err = 0;
> +
> +	list_for_each_entry_safe(elem, tmp, stash, list) {
> +		int ret = globalvar_set(elem->key, elem->value);
> +		if (ret)
> +			err = ret;
> +		globalvar_stashed_free(elem);
> +	}
> +
> +	return err;
> +}
> +
>  static int globalvar_simple_set(struct bobject *bobj, struct param_d *p,
>  				const char *val)
>  {
> diff --git a/include/globalvar.h b/include/globalvar.h
> index 413cf72002a0..1d39849ddbab 100644
> --- a/include/globalvar.h
> +++ b/include/globalvar.h
> @@ -24,6 +24,9 @@ char *globalvar_get_match(const char *match, const char *separator);
>  void globalvar_set_match(const char *match, const char *val);
>  int globalvar_set(const char *name, const char *val);
>  
> +int globalvar_stash_push(struct list_head *stash, ...) __attribute__((sentinel));
> +int globalvar_stash_pop(struct list_head *stash);
> +
>  int globalvar_add_simple_string(const char *name, char **value);
>  int globalvar_add_simple_int(const char *name, int *value,
>  			     const char *format);
> -- 
> 2.47.3
> 
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH 2/2] globalvar: add helpers for stashing global variables

[Ahmad Fatoum]

Hello Sascha,

On 3/18/26 09:12, Sascha Hauer wrote:
> On Thu, Mar 12, 2026 at 03:43:16PM +0100, Ahmad Fatoum wrote:
>> Configuring a FIT image boot with overlays involves setting not only
>> global.bootm.* variables, but also global.of.overlay.* variables.
>>
>> For use in custom boot entry functions, provide functions for stashing
>> and restoring a set of variables. This allows dry run and boot fallback
>> behavior to not affect later boot attempts.
> 
> Looks generally good. I assume this is to replace the .dyn. type
> variables, right?

Not on its own, because there is no means to use this from scripts.
For the .dyn. case I was thinking about a locally scope bootm bobject
that can be modified in the boot script and then discarded afterwards.

> Can we the a user before applying this?

The single user on my side is out-of-tree board code that uses it scope
use of global.of.overlay.filter Here's an excerpt:

 LIST_HEAD(stash);

 globalvar_stash_push(stash, "of.overlay.pattern", "of.overlay.filter", 
                      "of.overlay.path", NULL);

 globalvar_set("of.overlay.path", kernel);                              
 globalvar_set("of.overlay.filter", "pattern");                         
 globalvar_set("of.overlay.pattern", pattern);                          

 ret = bootm_entry(entry, &bootm_data);

 globalvar_stash_pop(&stash);


Thanks,
Ahmad

> 
> Sascha
> 
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> ---
>>  common/globalvar.c  | 77 +++++++++++++++++++++++++++++++++++++++++++++
>>  include/globalvar.h |  3 ++
>>  2 files changed, 80 insertions(+)
>>
>> diff --git a/common/globalvar.c b/common/globalvar.c
>> index c2b0d5b4bbad..e168d6055347 100644
>> --- a/common/globalvar.c
>> +++ b/common/globalvar.c
>> @@ -461,6 +461,83 @@ int globalvar_set(const char *name, const char *val)
>>  	return dev_set_param(&global_device, name, val);
>>  }
>>  
>> +struct globalvar_stashed {
>> +	const char *key;
>> +	const char *value;
>> +	struct list_head list;
>> +};
>> +
>> +static void globalvar_stashed_free(struct globalvar_stashed *elem)
>> +{
>> +	list_del(&elem->list);
>> +	free_const(elem->key);
>> +	free_const(elem->value);
>> +	free(elem);
>> +}
>> +
>> +int globalvar_stash_push(struct list_head *stash, ...)
>> +{
>> +	struct globalvar_stashed *elem, *safe;
>> +	const char *name;
>> +	int ret = -ENOMEM;
>> +	va_list args;
>> +	LIST_HEAD(tmp);
>> +
>> +	va_start(args, stash);
>> +
>> +	while ((name = va_arg(args, const char *))) {
>> +		const char *value;
>> +
>> +		elem = calloc(1, sizeof(*elem));
>> +		if (!elem)
>> +			goto out;
>> +
>> +		list_add_tail(&elem->list, &tmp);
>> +
>> +		elem->key = strdup_const(name);
>> +		if (!elem->key)
>> +			goto out;
>> +
>> +		value = globalvar_get(name);
>> +		if (!value) {
>> +			ret = -EINVAL;
>> +			goto out;
>> +		}
>> +
>> +		elem->value = strdup_const(value);
>> +		if (!elem->value)
>> +			goto out;
>> +	}
>> +
>> +	list_splice_tail(&tmp, stash);
>> +
>> +	ret = 0;
>> +out:
>> +	va_end(args);
>> +
>> +	if (ret) {
>> +		list_for_each_entry_safe(elem, safe, &tmp, list)
>> +			globalvar_stashed_free(elem);
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +int globalvar_stash_pop(struct list_head *stash)
>> +{
>> +	struct globalvar_stashed *elem, *tmp;
>> +	int err = 0;
>> +
>> +	list_for_each_entry_safe(elem, tmp, stash, list) {
>> +		int ret = globalvar_set(elem->key, elem->value);
>> +		if (ret)
>> +			err = ret;
>> +		globalvar_stashed_free(elem);
>> +	}
>> +
>> +	return err;
>> +}
>> +
>>  static int globalvar_simple_set(struct bobject *bobj, struct param_d *p,
>>  				const char *val)
>>  {
>> diff --git a/include/globalvar.h b/include/globalvar.h
>> index 413cf72002a0..1d39849ddbab 100644
>> --- a/include/globalvar.h
>> +++ b/include/globalvar.h
>> @@ -24,6 +24,9 @@ char *globalvar_get_match(const char *match, const char *separator);
>>  void globalvar_set_match(const char *match, const char *val);
>>  int globalvar_set(const char *name, const char *val);
>>  
>> +int globalvar_stash_push(struct list_head *stash, ...) __attribute__((sentinel));
>> +int globalvar_stash_pop(struct list_head *stash);
>> +
>>  int globalvar_add_simple_string(const char *name, char **value);
>>  int globalvar_add_simple_int(const char *name, int *value,
>>  			     const char *format);
>> -- 
>> 2.47.3
>>
>>
>>
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |