Re: Raspberry Pi 3B: /dev/mem mmap GPIO works on earmv7hf but not on aarch64

To: Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>, port-arm%NetBSD.org@localhost
Subject: Re: Raspberry Pi 3B: /dev/mem mmap GPIO works on earmv7hf but not on aarch64
From: Nick Hudson <nick.hudson%gmx.co.uk@localhost>
Date: Mon, 16 Feb 2026 19:34:25 +0000

On 16/02/2026 18:33, Izumi Tsutsui wrote:

Hi,

[snip]

Questions
---------

- Is /dev/mem + mmap expected to work for BCM283x/2711 peripheral MMIO
   on evbarm/aarch64?


No. It's lucky it works on evbarmv7.

- If yes, where should I look for the correct mapping attributes
   (device vs normal cacheable) for /dev/mem mappings on aarch64?


They don't exist.

- Does the described behavior sound like a cache attribute / pmap issue,
   or could it be an address translation issue?


There is no support for device type memory mappings via /dev/mem

What's wrong with gpioctl(8)?

Follow-Ups:
- Re: Raspberry Pi 3B: /dev/mem mmap GPIO works on earmv7hf but not on aarch64
  - From: Jason Thorpe

References:
- Raspberry Pi 3B: /dev/mem mmap GPIO works on earmv7hf but not on aarch64
  - From: Izumi Tsutsui

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