On 08/08/2017 04:28 AM, Peter Zijlstra wrote: > On Mon, Aug 07, 2017 at 01:36:39PM -0700, Paul E. McKenney wrote: >> On Mon, Aug 07, 2017 at 04:06:09PM -0400, Prarit Bhargava wrote: > >>> peterz? Want to offer a suggestion? The issue is that I'm changing a bool >>> config option to an int and that impacts all the arch's defconfigs. John points >>> out that this is a lot of churn and we're both wondering if there's a better way >>> to do the configs. >> >> The usual approach is to keep the old bool Kconfig option, and add another >> int Kconfig option that depends on the original one. The tests for >> the int value get a bit more complex, but one way to handle this is to >> define a cpp macro something like the following: >> >> #ifdef CONFIG_OLD_OPTION >> #define CPP_NEW_OPTION 0 >> #else >> #define CPP_NEW_OPTION CONFIG_NEW_OPTION >> #endif >> >> Then use CPP_NEW_OPTION, where zero means disabled and other numbers >> select the available options. >> >> Adjust to suit depending on what values mean what. >> >> Another approach is to make the range of the new Kconfig option >> depend on the old option: >> >> config NEW_OPTION >> int "your description here" >> range 1 5 if OLD_OPTION >> range 0 0 if !OLD_OPTION >> default 0 >> help >> your help here >> >> Again, adjust to suit depending on what values mean what. > > Right this. Except I don't see the !OLD_OPTION working as expected. > A 'new' config will not include the old one, so the !OLD_OPTION thing > will 'always' be true. > > So your: > >> @@ -1,8 +1,46 @@ >> menu "printk and dmesg options" >> >> +choice >> + prompt "printk default clock" >> + config PRINTK_TIME_DISABLE >> + bool "Disabled" >> + help >> + Selecting this option disables the time stamps of printk(). >> + >> + config PRINTK_TIME_LOCAL >> + bool "Local Clock" >> + help >> + Selecting this option causes the time stamps of printk() to be >> + stamped with the unadjusted hardware clock. >> + >> + config PRINTK_TIME_BOOT >> + bool "CLOCK_BOOTTIME" >> + help >> + Selecting this option causes the time stamps of printk() to be >> + stamped with the adjusted boottime clock. >> + >> + config PRINTK_TIME_MONO >> + bool "CLOCK_MONOTONIC" >> + help >> + Selecting this option causes the time stamps of printk() to be >> + stamped with the adjusted monotonic clock. >> + >> + config PRINTK_TIME_REAL >> + bool "CLOCK_REALTIME" >> + help >> + Selecting this option causes the time stamps of printk() to be >> + stamped with the adjusted realtime clock. >> + >> +endchoice >> + >> config PRINTK_TIME > > Change that into something like: > > config PRINTK_CLOCK > > >> - bool "Show timing information on printks" >> + int "Show time stamp information on printks" >> depends on PRINTK >> + default 0 if PRINTK_TIME_DISABLE >> + default 1 if PRINTK_TIME_LOCAL > > And that into: > > default 1 if PRINTK_TIME_LOCAL || PRINTK_TIME > >> + default 2 if PRINTK_TIME_BOOT >> + default 3 if PRINTK_TIME_MONO >> + default 4 if PRINTK_TIME_REAL >> help >> Selecting this option causes time stamps of the printk() > > Then the old PRINTK_TIME symbol will auto-convert into the new > equivalent. > I don't think there's an easy code way around this. Essentially this Kconfig code boils down to properly evaluating config PRINTK_CLOCK default 1 if PRINTK_TIME default 0 where there is no Kconfig entry for PRINTK_TIME. If undefined CONFIG_PRINTK_TIME is used in a config, it is immediately scrubbed by the kconfig script so it doesn't "exist" when CONFIG_PRINTK_CLOCK is evaluated. The result of that is CONFIG_PRINT_CLOCK=0. I tried config PRINTK_TIME bool "old config option" then I end up with both a CONFIG_PRINTK_CLOCK=1 and a CONFIG_PRINTK_TIME=y in the resulting config which is confusing. I've debated using the other suggestion that Paul made but TBH (sorry Paul) it seems like I'm avoiding the real but noisy solution of s/PRINTK_TIME=y/PRINTK_TIME=1/g I'm obviously open to other suggestions... P. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
