I'm reading the ext4 superblock, but its s_checksum (offset 0x3FC) is always zero. Also the s_checksum_type (offset 0x175) field is zero as well, however according to https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#The_Super_Block it should be 1.

Why is that?

(I'm on Ubuntu VM, which is hosted by VMWare Fusion on MacPro)

1 Answer 1


The answer is simply that the value can be either 1 or 0. There is currently only one valid checksum type (indicated by the 0x175 field). However, a value of 0 for type means that no checksum is used. This appears to be the default for at least Debian-based distros. Checksumming can be enabled as described in the OP linked document:

tune2fs -O metadata_csum /dev/path/to/disk

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