Important message for Apple Silicon OpenBSD/arm64 users

As you may be aware, OpenBSD runs on Apple Silicon M series processors, thanks to the efforts of the OpenBSD/arm64 developers.

For those running our favorite operating system alongside the Apple product, sometimes special measures are needed, though.

Mark Kettenis (kettenis@) sent a message titled Important message for Apple Silicon OpenBSD/arm64 users to the misc@ and arm@ mailing lists, warning about possible firmware issues:

Subject:    Important message for Apple Silicon OpenBSD/arm64 users
From:       Mark Kettenis <mark.kettenis () xs4all ! nl>
Date:       2024-05-21 20:54:21

As indicated here:

  https://social.treehouse.systems/@AsahiLinux/112449204541186432

The system firmware that comes with macOS Sonoma 14.5 triggers a bug
in the m1n1 bootloader that is used to boot OpenBSD on these machines.
The bug will prevent OpenBSD from booting on some machines after the
macOS update has been installed.  The recommended fix is to update the
"stage1" m1n1 by booting into macOS and running:

  $ curl https://alx.sh | sh

choosing the 'm' option when prompted to upgrade as indicated in the
aforementioned post.  This should work even if you've already
installed the macOS update.

We've also released a new version of the "apple-boot" firmware (which
contains a "stage2" m1n1) that has a workaround for the bug. To
install this new firmware on OpenBSD 7.5 or -current, you can do:

  # fw_update
  # installboot sd0

This must be done before updating macOS.  You can verify that the
workaround is installed with the following command:

  # eeprom -p | grep m1n1
          asahi,m1n1-stage2-version: '1.4.14'

If the displayed version number is 1.4.14 or later, the workaround is
installed.

OpenBSD 7.4 users should upgrade to OpenBSD 7.5.

Cheers,

Mark

So time to do the upgrade and send a note of thanks to Mark and the other OpenBSD/arm64 developers.