A question for the default value of config option in Kconfig

Wayne Ren



I am just working on ARC em starter_kit.  There are several configurations for em_starter_kit, em7d, em9d, em11d.


Different configurations have different parameters, i.e. the default value of config option in kconfig. These parameters are defined in the



The default configuration of em_starterkit is em9d.  


Then I type “make em_starterkit menuconfig” to get into menuconfig, and change the soc to em7d.


RGF_NUM_BANKS of em9d is 2,     of em7d is 1.  


When the soc option is changed to em7d,   the default value of RGF_NUM_BANKS  is still 2.

It seems this value only can be changed manually.  The definitions in kconfig_defconfig seems just work once.


Then I did another interesting experiment. 

1st step: make BOARD=qemu_x86 menuconfig

2nd step:   change the ARCH from x86 to ARC; select em_starterkit;  make a switch between em7d and em9d


I find these default values can change according the change of soc.  The definitions in kconfig_defconfig works as expected



The above issue is not only for ARC,   I also try other arch and boards, it seems all arch also have such a issue, i.e. the default values cannot change according to different kconfig_defconfig files.



I explored this issue for some time,  didn’t find a reason to explain this, and no solution.


Is it a design or a bug of kconfig?


Does anyone know this? or can provide hints?





Wayne Ren.



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