This is a useful mechanism any time you have a way to update the saved environment outside of u-boot. This can be a tool like fw_setenv or could be a tool like we use in Chrome OS that modifies the variables in a binary image before flashing (see factory_setup/update_firmware_vars.py in http://git.chromium.org/git/chromiumos/platform/factory-utils).
Signed-off-by: Doug Anderson dianders@chromium.org --- common/env_common.c | 24 ++++++++++++++++++++++++ 1 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/common/env_common.c b/common/env_common.c index 71811c4..5938732 100644 --- a/common/env_common.c +++ b/common/env_common.c @@ -34,6 +34,19 @@
DECLARE_GLOBAL_DATA_PTR;
+/* + * Create a saved enviroment with this env variable set to "1" to merge the + * saved environment on top of the default environment. The idea is that your + * saved environment would just contain variables that you'd like to override + * from the default so that as you update u-boot (w/ potential changes to the + * default) you get all the updates. + * + * This is really most useful when you have a tool like fw_setenv to manage + * your saved environment. Using 'saveenv' to save your environment will saved + * the _merged_ environment (AKA it won't unmerge things). + */ +#define MERGE_WITH_DEFAULT "merge_with_default" + /************************************************************************ * Default settings to be used when no valid environment is found */ @@ -208,7 +221,18 @@ int env_import(const char *buf, int check) }
if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0)) { + char *merge_val; + gd->flags |= GD_FLG_ENV_READY; + merge_val = getenv(MERGE_WITH_DEFAULT); + + if (merge_val != NULL && merge_val[0] != '0') { + set_default_env(""); + himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', + H_NOCLEAR); + hdelete_r(MERGE_WITH_DEFAULT, &env_htab); + puts("Merged saved with default environment\n\n"); + } return 1; }