Difference between config, menuconfig and defconfig

On Mon, 19 Sep 2016 16:20:12 +0530, Madhu K said:

That means kernel maintainer will define default configuration for his
architecture not for all architecture, I mean kernel maintainer might have
defined configuration for x86, not for ARM, POWERPC and all, is my
understanding correct?, if not please correct me.

There's more than one defconfig file.  Even more than one per architecture.
For many, there's a separate defconfig for each board:

[/usr/src/linux-next] for i in arch/*/configs; do echo -n "$i: "; find $i -name '*defconfig' | wc -l; done
arch/arc/configs: 15
arch/arm/configs: 112
arch/arm64/configs: 1
arch/avr32/configs: 15
arch/blackfin/configs: 29
arch/c6x/configs: 5
arch/cris/configs: 4
arch/h8300/configs: 3
arch/hexagon/configs: 1
arch/ia64/configs: 6
arch/m32r/configs: 12
arch/m68k/configs: 19
arch/metag/configs: 4
arch/microblaze/configs: 2
arch/mips/configs: 61
arch/mn10300/configs: 2
arch/nios2/configs: 2
arch/openrisc/configs: 1
arch/parisc/configs: 8
arch/powerpc/configs: 99
arch/s390/configs: 4
arch/score/configs: 1
arch/sh/configs: 56
arch/sparc/configs: 2
arch/tile/configs: 2
arch/um/configs: 2
arch/unicore32/configs: 1
arch/x86/configs: 2
arch/xtensa/configs: 6

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