Is it possible to make a part of a block device to be seen as a separate block device (in a similar way block 'devices' are created for partitions)? Unfortunately, I can't mount it through loop device due to poor performance. Also, I can't add a partition table to the disk. Hardcoding necessary information into the kernel is a possible option if someone shows where to put what.
addpart (from util-linux) to tell the kernel about partitions on a device.
SYNOPSIS addpart device partition start length DESCRIPTION addpart is a program that informs the Linux kernel of new par‐ tition. This command doesn't manipulate partitions on hard drive.