I was just running binwalk on certain OpenWRT images just to see how the layout of the final compressed images. I downloaded some 18.06.1 release images specifically for two routers, D-Link DIR-825, TRENDNet TEW-673GRU. The top level layout looks as follows:
uImage Header | LZMA Compressed Data | SquashFS Filesystem
When I decompress the LZMA data which contains the embedded kernel image there seems to be ~2-3MB data blobs at the beginning of the uncompressed LZMA data right before the embedded kernel image. Could anyone tell me what purpose do these data blobs serve?