I updated to the SOM to the image 2.7b4 from an older image version.
The Linux kernel boots but is not able to mount the rootfs with the following output which is then followed by a backtrace:
[ 3.109371] EXT4-fs (mmcblk0p2): couldn't mount as ext3 due to feature incompatibilities
[ 3.117676] List of all partitions:
[ 3.121229] 0100 65536 ram0 (driver?)
[ 3.125959] 0101 65536 ram1 (driver?)
[ 3.130647] 0102 65536 ram2 (driver?)
[ 3.135373] 0103 65536 ram3 (driver?)
[ 3.140061] 0104 65536 ram4 (driver?)
[ 3.144767] 0105 65536 ram5 (driver?)
[ 3.149462] 0106 65536 ram6 (driver?)
[ 3.154176] 0107 65536 ram7 (driver?)
[ 3.158864] 0108 65536 ram8 (driver?)
[ 3.166761] 0109 65536 ram9 (driver?)
[ 3.174673] 010a 65536 ram10 (driver?)
[ 3.182604] 010b 65536 ram11 (driver?)
[ 3.190512] 010c 65536 ram12 (driver?)
[ 3.198368] 010d 65536 ram13 (driver?)
[ 3.206155] 010e 65536 ram14 (driver?)
[ 3.213965] 010f 65536 ram15 (driver?)
[ 3.221690] b300 3866624 mmcblk0 driver: mmcblk
[ 3.230011] b301 16384 mmcblk0p1 ded30c96-01
[ 3.238343] b302 3846144 mmcblk0p2 ded30c96-02
[ 3.246676] b310 2048 mmcblk0boot1 (driver?)
[ 3.255014] b308 2048 mmcblk0boot0 (driver?)
[ 3.263310] 0800 29313144 sda driver: sd
[ 3.270890] 0801 1002708 sda1 2c1c6762-01
[ 3.278710] 0802 28308892 sda2 2c1c6762-02
[ 3.286506] No filesystem could mount root, tried: ext3
[ 3.294735] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,2)
How can I make the kernel mount the rootfs again?