NetBSD Playing with disklabels

A hands-on exploration of NetBSD 11's BSD disklabel format on x86_64, examining how disklabels are located on disk and manually decoding the raw hex bytes of the label header and partition table using disklabel.h and the disklabel(5) man page. The author writes a small C program to find the label's sector offset, walks through fields like d_magic, d_secsize, d_npartitions, and per-partition p_size/p_offset/p_fstype, verifies a checksum algorithm by reimplementing it with dd, od, and gawk, and then manually edits the hex dump to add a new ZFS partition, confirming the result with the disklabel command.

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