mkdosfs rounds reserved sectors to cluster size

Binary package hint: dosfstools

Some embedded devices require a FAT file-system with one, and only one reserved sector.
Specifically this is documented at http://www.xilinx.com/support/answers/14456.htm

mkdosfs.c lines 1060 and 1061 contains
    /* Adjust the reserved number of sectors for alignment */
    reserved_sectors = align_object(reserved_sectors, bs.cluster_size);

This rounds the number of reserved sectors up to the cluster size, preventing the creation of only one reserved sector.
Removing these two lines fixes the problem and returns the default number of reserved sectors to 1 for FAT12/16 and 32 for FAT32.

Ubuntu 10.10
dosfstools:
  Installed: 3.0.9-1
  Candidate: 3.0.9-1
  Version table:
 *** 3.0.9-1 0
        500 http://za.archive.ubuntu.com/ubuntu/ maverick/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: dosfstools 3.0.9-1 [modified: sbin/mkdosfs]
ProcVersionSignature: Ubuntu 2.6.35-28.49-generic 2.6.35.11
Uname: Linux 2.6.35-28-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Thu Mar 31 09:17:27 2011
ProcEnviron:
 SHELL=/bin/bash
 LANG=en_ZA.utf8
SourcePackage: dosfstools