[SOLVED] Z83-4: Boot to EFI Shell, no Filesystem recognized

Nolcad

New member
Good day!

My Minix Z83-4 did not want to wake up this morning. He may have gotten ill, I suppose.

The symptoms are:
  1. Boots directly to EFI Shell.
  2. No filesystem is listed (only blk0, blk1 and blk2).
  3. The UEFI does not list the Windows boot manager anymore
  4. Any USB key is not showing either in the EFI Shell (blk3 appears, no filesystem...)
I cannot use a Win10 recovery USB, a BIOS flash utility or any other type of bootable media.

Any help or advice, doctor?

Thierry
 
Self answering and describing the hard way to resolve for the poor souls around who would face the issue.

The problem was that the UEFI flash got corrupted somehow, probably because of an untimely power failure. The result of the corruption "removed" some of the UEFI disk drivers.

During normal operation, the UEFI builds a chain of drivers the following way, taking an USB drive as example:
USB port driver -> USB Mass Storage driver -> Generic disk driver -> Partition driver -> File System driver
In my case, the generic disk driver went away, and consequently all the file systems were not available anymore.

I used a Raspberry Pi and a level adapter (3.3V -> 1.8V) to physically re-flash the UEFI using BIOS 1.8 binary image on the board and did recover all my data.

The attached picture describes the quick and dirty setup I hacked during lunchtime:
UEFI_flash_setup.jpg

For the bold ones:
  • The UEFI flash (Winbond W25Q64FW) is a 1.8V chip. Do not attempt to flash using cheap programmers that may only handle 3.3V.
  • I used a make-do level converter using a 74LVC08 for pins CS, MOSI and SCK. MISO is an output from the flash and the Raspberry Pi can use the 0-1.8V levels directly
  • I used "flashrom" with the following parameters:
    • flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=1000 --write CHT0A180.bin
  • The connection to the flash is the following:
    • Flash (1) /CS <- Raspberry (24) through level converter
    • Flash (2) DO/MISO -> Raspberry (21) direct connect
    • Flash (3) /WP -- NC
    • Flash (4) GND <- Raspberry (25) and 2.8V power supply GND
    • Flash (5) DI/MOSI <- Raspberry (19) through level converter
    • Flash (6) CLK <- Raspberry (23) through level converter
    • Flash (7) /HOLD -- NC
    • Flash (8) VCC <- 2.8V power supply (No connection to the Raspberry Pi)
 
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