2a92080d8c4 [PATCH] efi_loader: add file/filesys support implemented the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.
Unfortunately it assumes that the available media are constant.
iPXE offers the possibility to attach iSCSI targets. On the handle for the attached target the EFI_BLOCK_IO_PROTOCOL and the EFI_DEVICE_PATH_PROTOCOL are installed.
Afterwards the ConnectController boot service is called to connect drivers to the iSCSI target. This relates to the following statement in the UEFI spec:
The firmware automatically creates handles for any block device that supports the following file system formats: - FAT12 - FAT16 - FAT32
iPXE expects that the driver for the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL gets installed to a child handle representing the partitions of the attached iSCSI target.
So I think we have to rewrite the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL implementation as an UEFI driver. The driver handle shall implement the EFI_DRIVER_BINDING_PROTOCOL. For each attached disk we shall call the ConnectController boot service. It will call the supported() service for the driver binding protocol and in case of success the start() service. The driver will in turn install the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL on the block io device.
The same pattern could be applied to the simple EFI_SIMPLE_NETWORK_PROTOCOL and the EFI_GRAPHICS_OUTPUT_PROTOCOL.
I now wonder what would be the best design. Should we have a uclass comprising all UEFI drivers? This would allow generating the UEFI driver handles by iterating the members of the uclass.
Looking forward to your ideas.
Best regards
Heinrich