So Santa brought you an M1 Mac: here’s what you should know

If you woke up this morning to a brand new M1 Mac, you’ll no doubt already be using it. Information about the many changes they bring is spread across many different pages here: this article is an introduction to some of their highlights and quirks. I hope it will save you making some basic errors, like holding Command-R when you want to enter Recovery Mode, or expecting to see the Startup Manager when you hold the Option key.

Update to macOS 11.1

If your M1 Mac has arrived with macOS 11.0 pre-installed, the first thing you should do – even before you think about migrating from another Mac – is update it to macOS 11.1. The step from 11.0 to 11.0.1 is the most important, as it ensures that all its new features work properly, and brings an essential firmware update.

It’s not just faster

I have a couple of explainers which look at some of the changed concepts in the M1 Macs. This article covers how it uses unified memory to its advantage, and this one looks at Apple’s changes in hardware design.

Apps and code

By and large, apps which are compatible with late versions of Catalina should run fine on your M1 Mac. If they come as Universal Apps, then they will run native on the M1’s cores; otherwise Rosetta 2 will translate their code from Intel to ARM. It does an excellent job, and translated code runs almost as fast as on Intel Macs.

This article looks some of the rare issues which you could encounter. If you create your own code to run native on an M1 Mac, you’ll need to sign it, as explained here. There are some other issues which you’ll need to be aware of, most significantly that M1 Macs run single-architecture toolchains, as explained here.

M1 Macs can only load Universal (or ARM-only) kernel extensions, which I’ve explored here.

Time Machine and APFS

If your previous Mac isn’t already making backups using Time Machine to an APFS volume, consider this as an excellent option with your M1 Mac. These new backups are much quicker and more efficient, although they aren’t backward-compatible. Setting them up is simple, as I detail here.

Recovery mode and more

Apple has completely reorganised the different startup modes, and how you enter them. This article summarises them conveniently to help you navigate the M1’s new startup options and modes.

External disks

There are currently limitations in what you can do with external disks in the way of starting up from them. Although you might be lucky in installing Big Sur onto an external disk so that you can start up from it, this isn’t guaranteed. At first I found it impossible using a SATA/USB-C SSD, but here detail how it should be more reliable with a Thunderbolt 3 SSD.

Unlike an Intel Mac with a T2 chip, M1 Macs start up from external disks without needing you to enter Recovery Mode and change their Secure Boot settings, provided that your external disk contains a bootable copy of Big Sur. However, the Startup Manager has become subsumed in the M1’s new Options, which you have to select from the first screen in Recovery Mode. You’ll probably find it easier to use the Startup Disk pane instead, when you can.

Currently, cloning of your internal disk’s System volume isn’t supported, although that should change soon. If you want an external disk to contain a copy of your System, the only way at present is using a Big Sur installer, as explained here.

Target Disk changes

M1 Macs no longer support a traditional target mode, in which you can directly access their internal storage by connecting them back-to-back with another Mac using a peripheral connection such as Thunderbolt. Instead, as explained here, they offer a high-speed SMB connection instead.

Firmware and updates

Check your M1 Mac’s iBoot firmware version with this table, and my free utilities SilentKnight 1.15 and LockRattler 4.30 give more information about the M1’s new platform security settings.

Volumes and paths

In both Catalina and Big Sur, the new boot Volume Group consisting of System and Data volumes can get very confusing. I’ve provided maps of boot volume layouts and some further hints on some of the trickier paths.

One oddity with the new Sealed System Volume in Big Sur is that almost all Macs running macOS 11 have their boot system snapshot correctly sealed, but the System volume isn’t. If you find this puzzling, this article explains more.

Disaster recovery

If all goes horribly wrong, you can restore your M1 Mac’s firmware and macOS using Apple’s free Configurator 2 app from the App Store, together with another Mac. This may appear daunting at first, but these tips may help you. That article includes links to Mr Macintosh’s collection of image files to support full restore. Unlike Intel Macs, you can use this to restore an older version of the iBoot firmware as well, making it a powerful recovery tool.

Technical matters

Documenting M1 Macs is only just under way. This article provides some basic information, and this analyses what happens during startup. Finally, be aware that not all Universal binaries work the same in both modes, as explained here.

Have great fun, and a very happy Christmas!