| Message ID | 20200522020223.230834-2-sjg@chromium.org |
|---|---|
| State | New |
| Headers | show |
| Series | [1/6] bootstage: Fix 'stacked' typo | expand |
On Fri, May 22, 2020 at 11:02 AM Simon Glass <sjg at chromium.org> wrote: > > At present if an optional Kconfig value needs to be used it must be > bracketed by #ifdef. For example, with this Kconfig setup: > > config WIBBLE > bool "Support wibbles, the world needs more wibbles" > > config WIBBLE_ADDR > hex "Address of the wibble" > depends on WIBBLE I am not sure if this is a good idea. If you want to always use CONFIG_WIBBLE_ADDR, you can get rid of 'depends on WIBBLE'. > then the following code must be used: > > #ifdef CONFIG_WIBBLE > static void handle_wibble(void) > { > int val = CONFIG_WIBBLE_ADDR; > > ... > } > #endif > > static void init_machine() > { > ... > #ifdef CONFIG_WIBBLE > handle_wibble(); > #endif > } > > Add a new IF_ENABLED_INT() to help with this. So now it is possible to > write, without #ifdefs: > > static void handle_wibble(void) > { > int val = IF_ENABLED_INT(CONFIG_WIBBLE, CONFIG_WIBBLE_ADDR); > > ... > } > > static void init_machine() > { > ... > if (IS_ENABLED(CONFIG_WIBBLE)) > handle_wibble(); > } > > The value will be 0 if CONFIG_WIBBLE is not defined, and > CONFIG_WIBBLE_ADDR if it is. This allows us to reduce the use of #ifdef in > the code, ensuring that the compiler still checks the code even if it is > not ultimately used for a particular build. > > Signed-off-by: Simon Glass <sjg at chromium.org> > --- > > include/linux/kconfig.h | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h > index 3a2da738c4..86cd266540 100644 > --- a/include/linux/kconfig.h > +++ b/include/linux/kconfig.h > @@ -79,6 +79,18 @@ > */ > #define CONFIG_VAL(option) config_val(option) > > +/* This use a similar mechanism to config_enabled() above */ > +#define config_opt_enabled(cfg, opt_cfg) _config_opt_enabled(cfg, opt_cfg) > +#define _config_opt_enabled(cfg_val, opt_value) \ > + __config_opt_enabled(__ARG_PLACEHOLDER_##cfg_val, opt_value) > +#define __config_opt_enabled(arg1_or_junk, arg2) \ > + ___config_opt_enabled(arg1_or_junk arg2, 0) > +#define ___config_opt_enabled(__ignored, val, ...) val > + > +/* Evaluates to 0 if option is not defined, int_option if it is defined */ > +#define IF_ENABLED_INT(option, int_option) \ > + config_opt_enabled(option, int_option) > + > /* > * CONFIG_IS_ENABLED(FOO) evaluates to > * 1 if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'y' or 'm', > -- > 2.27.0.rc0.183.gde8f92d652-goog >
On 5/22/20 4:17 AM, Masahiro Yamada wrote: > On Fri, May 22, 2020 at 11:02 AM Simon Glass <sjg at chromium.org> wrote: >> >> At present if an optional Kconfig value needs to be used it must be >> bracketed by #ifdef. For example, with this Kconfig setup: >> >> config WIBBLE >> bool "Support wibbles, the world needs more wibbles" >> >> config WIBBLE_ADDR >> hex "Address of the wibble" >> depends on WIBBLE > > > > > I am not sure if this is a good idea. > > > If you want to always use CONFIG_WIBBLE_ADDR, > you can get rid of 'depends on WIBBLE'. > > Hello Simon, what is the effect on the code size if you eliminate the #ifdefs? Isn't this move growing the size of the U-Boot binary? Best regards Heinrich > > >> then the following code must be used: >> >> #ifdef CONFIG_WIBBLE >> static void handle_wibble(void) >> { >> int val = CONFIG_WIBBLE_ADDR; >> >> ... >> } >> #endif >> >> static void init_machine() >> { >> ... >> #ifdef CONFIG_WIBBLE >> handle_wibble(); >> #endif >> } >> >> Add a new IF_ENABLED_INT() to help with this. So now it is possible to >> write, without #ifdefs: >> >> static void handle_wibble(void) >> { >> int val = IF_ENABLED_INT(CONFIG_WIBBLE, CONFIG_WIBBLE_ADDR); >> >> ... >> } >> >> static void init_machine() >> { >> ... >> if (IS_ENABLED(CONFIG_WIBBLE)) >> handle_wibble(); >> } >> >> The value will be 0 if CONFIG_WIBBLE is not defined, and >> CONFIG_WIBBLE_ADDR if it is. This allows us to reduce the use of #ifdef in >> the code, ensuring that the compiler still checks the code even if it is >> not ultimately used for a particular build. >> >> Signed-off-by: Simon Glass <sjg at chromium.org> >> --- >> >> include/linux/kconfig.h | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h >> index 3a2da738c4..86cd266540 100644 >> --- a/include/linux/kconfig.h >> +++ b/include/linux/kconfig.h >> @@ -79,6 +79,18 @@ >> */ >> #define CONFIG_VAL(option) config_val(option) >> >> +/* This use a similar mechanism to config_enabled() above */ >> +#define config_opt_enabled(cfg, opt_cfg) _config_opt_enabled(cfg, opt_cfg) >> +#define _config_opt_enabled(cfg_val, opt_value) \ >> + __config_opt_enabled(__ARG_PLACEHOLDER_##cfg_val, opt_value) >> +#define __config_opt_enabled(arg1_or_junk, arg2) \ >> + ___config_opt_enabled(arg1_or_junk arg2, 0) >> +#define ___config_opt_enabled(__ignored, val, ...) val >> + >> +/* Evaluates to 0 if option is not defined, int_option if it is defined */ >> +#define IF_ENABLED_INT(option, int_option) \ >> + config_opt_enabled(option, int_option) >> + >> /* >> * CONFIG_IS_ENABLED(FOO) evaluates to >> * 1 if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'y' or 'm', >> -- >> 2.27.0.rc0.183.gde8f92d652-goog >> > >
Hi, On Fri, 22 May 2020 at 00:18, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote: > > On 5/22/20 4:17 AM, Masahiro Yamada wrote: > > On Fri, May 22, 2020 at 11:02 AM Simon Glass <sjg at chromium.org> wrote: > >> > >> At present if an optional Kconfig value needs to be used it must be > >> bracketed by #ifdef. For example, with this Kconfig setup: > >> > >> config WIBBLE > >> bool "Support wibbles, the world needs more wibbles" > >> > >> config WIBBLE_ADDR > >> hex "Address of the wibble" > >> depends on WIBBLE > > > > > > > > > > I am not sure if this is a good idea. > > > > > > If you want to always use CONFIG_WIBBLE_ADDR, > > you can get rid of 'depends on WIBBLE'. Yes that's right. But I worry that we end up clutting the Kconfig with unused things. Another option would be for Kconfig to emit hex CONFIGs always, even if optional? > > > > > > Hello Simon, > > what is the effect on the code size if you eliminate the #ifdefs? > > Isn't this move growing the size of the U-Boot binary? No it is handled at compile time so the code doesn't make it into the image. [..] Regards, Simon
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h index 3a2da738c4..86cd266540 100644 --- a/include/linux/kconfig.h +++ b/include/linux/kconfig.h @@ -79,6 +79,18 @@ */ #define CONFIG_VAL(option) config_val(option) +/* This use a similar mechanism to config_enabled() above */ +#define config_opt_enabled(cfg, opt_cfg) _config_opt_enabled(cfg, opt_cfg) +#define _config_opt_enabled(cfg_val, opt_value) \ + __config_opt_enabled(__ARG_PLACEHOLDER_##cfg_val, opt_value) +#define __config_opt_enabled(arg1_or_junk, arg2) \ + ___config_opt_enabled(arg1_or_junk arg2, 0) +#define ___config_opt_enabled(__ignored, val, ...) val + +/* Evaluates to 0 if option is not defined, int_option if it is defined */ +#define IF_ENABLED_INT(option, int_option) \ + config_opt_enabled(option, int_option) + /* * CONFIG_IS_ENABLED(FOO) evaluates to * 1 if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'y' or 'm',
At present if an optional Kconfig value needs to be used it must be bracketed by #ifdef. For example, with this Kconfig setup: config WIBBLE bool "Support wibbles, the world needs more wibbles" config WIBBLE_ADDR hex "Address of the wibble" depends on WIBBLE then the following code must be used: #ifdef CONFIG_WIBBLE static void handle_wibble(void) { int val = CONFIG_WIBBLE_ADDR; ... } #endif static void init_machine() { ... #ifdef CONFIG_WIBBLE handle_wibble(); #endif } Add a new IF_ENABLED_INT() to help with this. So now it is possible to write, without #ifdefs: static void handle_wibble(void) { int val = IF_ENABLED_INT(CONFIG_WIBBLE, CONFIG_WIBBLE_ADDR); ... } static void init_machine() { ... if (IS_ENABLED(CONFIG_WIBBLE)) handle_wibble(); } The value will be 0 if CONFIG_WIBBLE is not defined, and CONFIG_WIBBLE_ADDR if it is. This allows us to reduce the use of #ifdef in the code, ensuring that the compiler still checks the code even if it is not ultimately used for a particular build. Signed-off-by: Simon Glass <sjg at chromium.org> --- include/linux/kconfig.h | 12 ++++++++++++ 1 file changed, 12 insertions(+)