On Fri, Mar 27, 2020 at 12:02:00AM +0100, Rasmus Villemoes wrote:
Deciding whether to compile the env_sf_save() function based solely on CONFIG_SPL_BUILD is wrong: For U-Boot proper, it leads to a build warning in case CONFIG_CMD_SAVEENV=n (because the initialization of the .save member is guarded by CONFIG_CMD_SAVEENV, while the env_sf_save() function is built if !CONFIG_SPL_BUILD - and even without the CONFIG_CMD_SAVEENV guard, the env_save_ptr() macro would just expand to NULL, with no reference to env_sf_save visible to the compiler). And for SPL, when one selects CONFIG_SPL_SAVEENV, one obviously expects to actually be able to save the environment.
The compiler warning can be fixed by using a "<something> ? env_sf_save : NULL" construction instead of a macro that just eats its argument and expands to NULL. That way, if <something> is false, env_sf_save gets eliminated as dead code, but the compiler still sees the reference to it.
For <something>, we can use CONFIG_IS_ENABLED(SAVEENV), which is true precisely:
- For U-Boot proper, when CONFIG_CMD_SAVEENV is set (because CONFIG_SAVEENV is a hidden config symbol that gets set if and only if CONFIG_CMD_SAVEENV is set).
- For SPL, when CONFIG_SPL_SAVEENV is set.
As a bonus, this also removes quite a few preprocessor conditionals.
This has been run-time tested on a mpc8309-derived board to verify that saving the environment does indeed work in SPL with these patches applied.
Signed-off-by: Rasmus Villemoes rasmus.villemoes@prevas.dk
Applied to u-boot/master, thanks!