It boots fine from disk (windows) and from a thumbdrive (arch live image) in the keyboard, but I can't seem to boot from a micro-SD card (arch installed with the thumbdrive). I have the gut feeling that the EFI shell simply doesn't know what the card reader is because map only lists:
- FS0 (/PciRoot(0x0)/Pci(0x14)/USB(0x3)/USB(0x2)/HD(1,MBR)),
- FS1 (/PciRoot(0x0)/Pci(0x17)/Ctrl(0x0)/HD(1,GPT)),
- BLK0 (/PciRoot(0x0)/Pci(0x14)/USB(0x3)/USB(0x2)),
- BLK2 (/PciRoot(0x0)/Pci(0x17)/Ctrl(0x0)),
- BLK4 (/PciRoot0/Pci17/Ctrl0/HD2),
- BLK5 (..HD3) and
- BLK6 (..HD4).
The internal disk has a GPT layout with a fat32 ESP, the thumbdrive has an MBR layout with a... iso9960 type 0 boot partition (maybe I should've formatted the thumbdrive as GPT before writing the live image; anyway, it works) and the sd card has a GPT layout with a fat32 ESP.
Also, with the thumbdrive live image lshw reports the thumbdrive at usb@1:3.2 and the sd card at usb@1:4.1.
Changing the windows ESP might be an option. (I'd rather not, but if there's some bootloader required to figure out where the SD card is and call the initramfs, so be it.)
Can I make the computer boot from an SD card? (And, if so, how?) (And, if not, could I successfully dd the whole internal disk, install arch on it and put the disk copy back later without side effects?)
Possible complications: in all my wisdom I made the root partition on the sd card an encrypted volume. And so far the boot partition does not have an EFI folder, but only initramfses.