Re:Don’t format a drive of M1 Macs from recovery mode
by m1mac on Thursday February 18, 2021 @07:42AM
(#26179143)
> Additionally, the SEP data is stored separately from the OS (in one of the volumes of the first container). To wipe that, after wiping the partition and before reinstalling, run `xartutil --erase-all`.
I believe the "Erase Mac" function in Recovery Assistant also erases the SEP data, based on the output of `xartutil --list` before and after. If I'm correct about that, going through Recovery Assistant should be the recommended way to fully erase an M1 Mac (short of a DFU restore through Apple Configurator which also restores firmware).
On T2 Macs, `xartutil --erase-all` would wipe all SEP data, including the encryption keys used for the drive. In other words, it was the equivalent of a secure erase and was my recommended way to fully erase a Mac before resale. I suspect Recovery Assistant is just doing the equivalent of `xartutil --erase-all`, but I haven't tried `xartutil --erase-all` on an M1 because I'm afraid to brick the machine to the point of needing a DFU restore, and I don't have another Mac at hand to run Apple Configurator with right now.
I believe the "Erase Mac" function in Recovery Assistant also erases the SEP data, based on the output of `xartutil --list` before and after. If I'm correct about that, going through Recovery Assistant should be the recommended way to fully erase an M1 Mac (short of a DFU restore through Apple Configurator which also restores firmware).
On T2 Macs, `xartutil --erase-all` would wipe all SEP data, including the encryption keys used for the drive. In other words, it was the equivalent of a secure erase and was my recommended way to fully erase a Mac before resale. I suspect Recovery Assistant is just doing the equivalent of `xartutil --erase-all`, but I haven't tried `xartutil --erase-all` on an M1 because I'm afraid to brick the machine to the point of needing a DFU restore, and I don't have another Mac at hand to run Apple Configurator with right now.