/dev/gpiomem versus /dev/mem - Raspberry Pi Forums

i posted following on "bare metal" , told linux question, i'm reposting here:

can point me discussion of difference between using /dev/gpiomem , /dev/mem access gpio? i've tried both. both work, , both require sudo run program they're used in.

i'm doing textbook. i'm inclined use /dev/mem because seems more general. when students graduate, chances won't programming raspberry pi in jobs.

here response got on "bare metal." looks wonder if has add. since textbook, want have thorough explanation.

this isn't bare metal question. it's linux question.

should not need use sudo /dev/gpiomem. required user belongs gpio group.

/dev/gpiomem grants access gpio peripheral registers.

/dev/mem grants access peripheral registers memory. more dangerous.

/dev/gpiomem doesn't require sudo access if user member of "gpio" group. "pi" user member of group.

difference between 2 /dev/mem allows access all arm accessible memory on pi, whilst /dev/gpiomem area associated gpio control.

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