Medkit cache on USB storage device
The idea behind this is to fix these two issues:
- Uboot implementation of TFTP is slow and download of image takes a long time
- In some cases it is not possible to download image at all as we do not have access to network from uboot (such as in case of SFP)
The design is to have one USB storage device connected to the board. It has to be formated to FAT32 (so we can read and write files to it from uboot). We can use files on it instead of medkit pushed from network. The idea is to download sha256sum file and use sum from there to see if we don't have it all prepared on cache storage (check that we have files HASH.{image,dtb,initrd}
). We can use cache if they are there. When they are not available in cache then we have to either download those images to board over network and save them to cache or boot rescue and download images that way and try again. The second approach targets the second issue (the inability to download image from uboot over the network)