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In linux kernel source, why is there only one defconfig file for arch/arm64? (for arch/arm there are many xxx_defconfig files)

In linux kernel 5.4.21, there are many xxx_defconfig files under arch/arm/configs.
But under arch/arm64/configs, there is only one file named "defconfig". Why is it so?

Solution

  • The original ARM was developed some years ago whereas ARM64 is more current. The desire would be to have only a single defconfig. However, some ARM32 systems have a limited boot loader instead of a modern u-boot capable of sending a device tree. Some of the 32 bit ARM systems may boot with 'ATAGS'. This is not supported with ARM64. These cases require specific configuration files.

    For the ARM64 you are free to make your own .config, but the kernel developers only need to support one and it should work on all systems (but be slightly bigger and includes modules).