Why kernel/drivers/char/virtd is a binary file?

[adgnaf]

Noticed that file kernel/drivers/char/virtd is a binary file and will be compiled into kernel image. Is the binary file benign?

[GMMan]

It's an eMMC RPMB driver. Since it deals with DRM, it's a blob in an attempt to conceal its workings, but it's got all the symbols, so just drop it into Ghidra or something if you want to know how it works. It's not a configurable build option, so if you don't need it or it's causing you problems, remove it from the Makefile, and also make sure to update drivers/mmc/card/block.c to remove references to mmc_blk_emmc_add() and mmc_blk_emmc_remove(), or you'll get linking errors.