Ubuntu
os-prober package

Bug #432254
Comment #7

Comment 7 for bug 432254

Revision history for this message

Peter Belew (peterbe) wrote on 2009-09-22: Re: FreeBSD not detected by os-prober

FreeBSD is installed in one or more primary partitions, which FreeBSD refers to as 'slices'. Then the slices are broken down into partitions, identified by lower-case letters. This subdivision is different from the usual DOS/Windows/IBM scheme of dividing extended partitions.

In Linux fdisk, a FreeBSD 'slice' is shown as type a5, OpenBSD as type a6, NetBSD as a9. You can see that by listing partition types in Linux fdisk. So on one of my systems, the fdisk 'p' command shows that I have

/dev/sda2 * 19 3665 29294055 a5 FreeBSD

Those partition types will help distinguish FreeBSD from its relatives, but I don't have any experience with the others, so I don't know how they are subdivided in those systems. PC-BSD is derived from FreeBSD, so I assume its partitioning is the same.

Linux can mount FreeBSD partitions, at least read-only. I have the following /etc/fstab entries on the same system:

#bsd partition(s)
# bsd: /dev/ad0s2a
/dev/sda8 /mnt/bsdroot ufs ro,ufstype=ufs2 0 0
# bsd: /dev/ad0s2f
/dev/sda12 /mnt/bsdusr ufs ro,ufstype=ufs2 0 0
# bsd: /dev/ad0s2g
/dev/sda13 /mnt/bsdhome ufs ro,ufstype=ufs2 0 0

The comments show what FreeBSD calls those partitions. You can see how the names are mapped on Linux by looking at

root@lightning:~# cat /proc/partitions
major minor #blocks name

so they look somewhat like DOS logical partitions inside an extended partition.

For the legacy Grub 1 on the same system, this will boot FreeBSD:

title FreeBSD 7.1
root (hd0,1,a)
kernel /boot/loader

So grub and Linux are able to access the UFS file system on the FreeBSD partitions.

It would probably help to install a minimal FreeBSD on a primary partition on your HD - I'll follow with a bit of information about that.

/dev/sda2   *          19        3665    29294055   a5  FreeBSD

Linux can mount FreeBSD partitions, at least read-only. I have the following /etc/fstab entries on the same system:

#bsd partition(s)
# bsd: /dev/ad0s2a
/dev/sda8       /mnt/bsdroot    ufs     ro,ufstype=ufs2 0       0
# bsd: /dev/ad0s2f
/dev/sda12      /mnt/bsdusr     ufs     ro,ufstype=ufs2 0       0
# bsd: /dev/ad0s2g
/dev/sda13      /mnt/bsdhome    ufs     ro,ufstype=ufs2 0       0

The comments show what FreeBSD calls those partitions. You can see how the names are mapped on Linux by looking at

root@lightning:~# cat /proc/partitions
major minor  #blocks  name

8        0   78150744 sda
   8        1     144553 sda1
   8        2   29294055 sda2
   8        3          1 sda3
   8        5   11719386 sda5
   8        6     979933 sda6
   8        7   36009666 sda7
   8        8     524288 sda8     '/' on FreeBSD
   8        9     949064 sda9
   8       10    1522688 sda10
   8       11     524288 sda11
   8       12   10485760 sda12 'usr' on FreeBSD
   8       13   15287967 sda13 '/home' on FreeBSD