It was foolish to hope to see a simple list of actions and commands without getting into the essence.
# /sbin/sfdisk --no-reread /dev/mmcblk0 -N1
/dev/mmcblk0p1 :16 128000 c
# /sbin/sfdisk --no-reread /dev/mmcblk0 -N4
/dev/mmcblk0p4 :128016 160496 L
# /sbin/sfdisk -l /dev/mmcblk0 Disk /dev/mmcblk0: 485120 cylinders, 4 heads, 16 sectors/track Units = cylinders of 32768 bytes, blocks of 1024 bytes, counting from 0 Device Boot Start End #cyls #blocks Id System /dev/mmcblk0p1 16 128015 128000 4096000 c W95 FAT32 (LBA) /dev/mmcblk0p2 288512 419583 131072 4194304 83 Linux /dev/mmcblk0p3 419584 485119 65536 2097152 83 Linux /dev/mmcblk0p4 128016 288511 160496 5135872 83 Linux ~ # /sbin/mkfs.ext4 /dev/mmcblk0p4 mke2fs 1.41.12maemo1 (17-May-2010) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=0 blocks, Stripe width=0 blocks 321280 inodes, 1283968 blocks 64198 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=1317011456 40 block groups 32768 blocks per group, 32768 fragments per group 8032 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 24 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.