How does the boot wallpaper get selected in big sur or monterey? If you boot an m1 imac, it will use a wallpaper that matches the colour of your mac.
I can see all the wallpapers are part of the blessed / sealed volume, what i can’t figure out is how it’s choosing with wallpaper to use?
To be clear I’m talking about the very early boot wallpaper before file vault is unlocked. This is not the (user configurable) login screen wallpaper. This is a fixed choice.
My best guess is an nvram key but i didn’t spy an obvious one.
As I understand it product information and iBoot1 are stored on an SPI flash chip in the device (which is hard to mess with from an OS unless you're quite determined to, but basically unrecoverable if you do), iBoot2 reads this information and uses it to select and fill in a device tree that is passed to your kernel.
I think you might be able to find this information if you do:
This is correct. As I understand it, Apple have a database of product information and if you do wipe your SPI flash, it will be restored by phoning home during the DFU restore process (by identifying your machine based on its fused in ECID), though I've yet to try this. So it should be in fact fully recoverable.
This information is in the system configuration area, and gets inserted into the device tree template by iBoot2. You can see the template DT and what sysconfig entries it pulls data from if you extract it from an OS restore image instead of looking at the runtime DT with ioreg.
I can see all the wallpapers are part of the blessed / sealed volume, what i can’t figure out is how it’s choosing with wallpaper to use?
To be clear I’m talking about the very early boot wallpaper before file vault is unlocked. This is not the (user configurable) login screen wallpaper. This is a fixed choice.
My best guess is an nvram key but i didn’t spy an obvious one.