[U-Boot] in Kbuild, what is the difference between "extra-" and "obj-"?

6 Jul
2016
6 Jul
'16
1:32 p.m.
admittedly, this is more a kernel Kbuild question, but in common/Makefile, i see the snippet:
extra-$(CONFIG_ENV_IS_EMBEDDED) += env_embedded.o obj-$(CONFIG_ENV_IS_IN_EEPROM) += env_embedded.o extra-$(CONFIG_ENV_IS_IN_FLASH) += env_embedded.o
what is the functional difference between using "extra-" and "obj-" in the above? those three lines look ... inconsistent?
anyway, what is going on there? thanks.
rday
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Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca
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