/proc/cpu/alignment is absent

[Fullmetal8ender]

Hi. I build this kernel, and notice that /proc/cpu/alignment is absent.
I need to enable SIGBUS signal to the user process performing the unaligned access.
Do I need to reconfigure kernel for /proc/cpu/alignment arrive, or there are another way to change the alignment trap behavior?

[pelwell]

/proc/cpu/alignment is present on builds using the Raspberry Pi defconfigs (bcm2709_defconfig and bcmrpi_defconfig). In order for the procfs entry to appear, CONFIG_PROC_FS must be defined, but otherwise it should be automatic for ARMs:

config ALIGNMENT_TRAP
	bool
	depends on CPU_CP15_MMU
	default y if !ARCH_EBSA110

Notice the default value.

[Fullmetal8ender]

Thank You for fast reply!
Does this works for aarch64 (rpi3)?
I create config with make ARCH=arm64 bcmrpi3_defconfig O=../out and there is no ALIGNMENT_TRAP.
Maybe aarch64 does not support CPU_CP15_MMU?

[pelwell]

You should have mentioned that yours was a 64-bit build - alignment trap is not available on any arm64 kernel.