as a final(?) example of one of my originally Linux kernel-related Kbuild cleanup scripts, i have one that identifies Makefile entries that refer to Kbuild options that are not defined in any Kconfig file (IIRC, they might be defined manually in a defconfig file, i'll have to refresh my memory, but tradition suggests that "CONFIG_"-prefixed variables are meant to be defined in Kconfig files).

i ran this script on the entire u-boot code base, and posted the results here (not overly long):

https://crashcourse.ca/dokuwiki/doku.php?id=u-boot_make_badref

so let me elaborate with a couple examples.

first, there's this output:

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NATSEMI

./drivers/net/Makefile:obj-$(CONFIG_NATSEMI) += natsemi.o

so what's the story with CONFIG_NATSEMI? first, it clearly is not defined in a Kconfig file anywhere:

$ git grep "config NATSEMI" $

so where does it occur?

$ git grep CONFIG_NATSEMI README: CONFIG_NATSEMI drivers/net/Makefile:obj-$(CONFIG_NATSEMI) += natsemi.o include/netdev.h:#ifdef CONFIG_NATSEMI scripts/config_whitelist.txt:CONFIG_NATSEMI $

pretty clearly(?), it's documented and tested and whitelisted, while never being defined anywhere. a wild guess suggests it really should say CONFIG_PHY_NATSEMI:

$ git grep CONFIG_PHY_NATSEMI configs/brppt1_mmc_defconfig:CONFIG_PHY_NATSEMI=y configs/brppt1_nand_defconfig:CONFIG_PHY_NATSEMI=y configs/brppt1_spi_defconfig:CONFIG_PHY_NATSEMI=y configs/microblaze-generic_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_versal_virt_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zc1751_xm015_dc1_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zc1751_xm016_dc2_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zc1751_xm017_dc3_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zc1751_xm018_dc4_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zc1751_xm019_dc5_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zcu102_rev1_0_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zcu102_revA_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zcu102_revB_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zcu104_revA_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zcu104_revC_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zcu106_revA_defconfig:CONFIG_PHY_NATSEMI=y configs/xilinx_zynqmp_zcu111_revA_defconfig:CONFIG_PHY_NATSEMI=y drivers/net/phy/Makefile:obj-$(CONFIG_PHY_NATSEMI) += natsemi.o drivers/net/phy/phy.c:#ifdef CONFIG_PHY_NATSEMI include/config_phylib_all_drivers.h:#define CONFIG_PHY_NATSEMI include/configs/pengwyn.h:#define CONFIG_PHY_NATSEMI include/configs/rut.h:#define CONFIG_PHY_NATSEMI include/configs/spear6xx_evb.h:#define CONFIG_PHY_NATSEMI $

as established back in 2015:

commit f96fe2c0a8a72d675532d79df49cbfe3464154a5 Author: Michal Simek michal.simek@xilinx.com Date: Wed Sep 23 19:35:31 2015 +0200

ARM64: zynqmp: Enable NATSEMI phys

Signed-off-by: Michal Simek michal.simek@xilinx.com

diff --git a/include/configs/xilinx_zynqmp.h b/include/configs/xilinx_zynqmp.h index 5008722bf4..eae1a4988b 100644 --- a/include/configs/xilinx_zynqmp.h +++ b/include/configs/xilinx_zynqmp.h @@ -193,6 +193,7 @@ # define CONFIG_MII # define CONFIG_SYS_FAULT_ECHO_LINK_DOWN # define CONFIG_PHY_MARVELL +# define CONFIG_PHY_NATSEMI # define CONFIG_PHY_TI #endif

and as a second (far more trivial) example, there's this:

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RTC_DAVINCI

./drivers/rtc/Makefile:obj-$(CONFIG_RTC_DAVINCI) += davinci.o

where does that string occur? apparently, in only one place so it clearly is utterly worthless as it is currently spelled:

$ git grep RTC_DAVINCI drivers/rtc/Makefile:obj-$(CONFIG_RTC_DAVINCI) += davinci.o $

anyway, people are free to peruse that page to see if anything jumps out at them. i'll spend a few minutes today wiki'ing all of the scripts so people can run them on whatever part of the code base amuses them. thanks for your patience.

rday