The medium a device like 'mmc 0' or 'usb 0' points to may change over time. Hence device type and number are not sufficient to identify the inserted medium. The same is true for the device path generated for such a device. This is why the EFI_BLOCK_IO_PROTOCOL provides a field MediaId.
Whenever a removable medium is changed or a new block device with a previously used device path is created we should provide a different MediaID.
This series adds a field media_id to the block device descriptor and fills it after probing. The value of the field is then copied to the EFI_BLOCK_IO_PROTOCOL.
With future patches we can refine this in sub-systems like USB, MMC, SCSI to indicate media changes
Heinrich Schuchardt (2): dm: blk: assign media ID to block devices efi_loader: fill media_id from block device descriptor
drivers/block/blk-uclass.c | 16 +++++++++++++++- include/blk.h | 11 +++++++++++ lib/efi_loader/efi_disk.c | 6 +----- 3 files changed, 27 insertions(+), 6 deletions(-)