Dear Simon,
In message CAPnjgZ3B4sZi_2h2Sw7oop932CcgOu8HO5E_fKmjcyv4wS+eZA@mail.gmail.com you wrote:
...
By chance I ran about "include/linux/kconfig.h" in the Linux kernel tree, which provides (among other things) the IS_ENABLED() macro that implements essentially the very same feature. Using this, the same code would be written as:
if (IS_ENABLED(CONFIG_VERSION_VARIABLE)) setenv("ver", version_string); /* set version variable */
...
Fair enough, sounds reasonable. The relevant kernel code is quite unusual...
Indeed, this code is really a bit creepy...
Many of U-Boot's options are not just yes/no, so I'm not sure what will happen with those. Perhaps they just can't be used with this macro? Part of my intent was to allow any option to be used.
I see. Um... But then, I think the usage of the macro is somewhat dangerous anyway.
So for example you can do this:
struct {
const char *str; u_int len; int retry; const char *conf; /* Configuration value */ } delaykey [] = { { str: getenv("bootdelaykey"), retry: 1, conf: autoconf_autoboot_delay_str() }, { str: getenv("bootdelaykey2"), retry: 1, conf: autoconf_autoboot_delay_str2() }, { str: getenv("bootstopkey"), retry: 0, conf: autoconf_autoboot_stop_str() }, { str: getenv("bootstopkey2"), retry: 0, conf: autoconf_autoboot_stop_str2() }, };
Well, this is not exactly easy to read either.
or this:
/* don't retry auto boot? */
if (autoconf_boot_retry_time() && !delaykey[i].retry) retry_time = -1;
Note that autoconf_boot_retry_time() will return 0 if the CONFIG is not defined, or if its value is 0.
I see what yo mean, but I'd rather clean up the code to avoid such ambiguities.
It seems to me we should provide the Linux feature in U-Boot as part of the Kconfig stuff, and see where it takes us. Combined with a bit more rationalisation of things like main.c it might be enough.
Sounds like a plan - but we don't have to wait; we can add the header file any time we ike, and start converting pieces of code that seem to deserve such treatment. And, probably even more interesting, we can request it to be used for any new code being added.
I like the simplicity and power of the autoconf feature, but I have similar reservations to others.
I understand you. Eventuyally ther eis no easy solution that satisfies all.
Best regards,
Wolfgang Denk