Re: using swap on a separate slice

[walt <wa1ter@xxxxxxxxxxxxx>]

On Sat, 23 Dec 2006, talon@lpthe.jussieu.fr wrote:

> walt wrote:
>
> > x ad0s4{a,b}, etc.).
> >
> > I just tried using my linux swap partition/slice on DF.  To avoid
> > the errors you mention I had to add a disklabel to the swap slice:
> >
> > #disklabel -w -r /dev/ad0s8 auto
> >
> > #swapon /dev/ad0s8
> >
> > # swapinfo
> > Device          1K-blocks     Used    Avail Capacity  Type
> > /dev/ad1s6b        524160        0   524160     0%    Interleaved
> > /dev/ad0s8         529984        0   529984     0%    Interleaved
> > Total             1054144        0  1054144     0%
> >
> > I'm guessing that if I now reboot into linux and anything swaps to
> > disk, my new disklabel will get trashed -- just something to keep
> > in mind for us OS junkies ;o)
>
> I am routinely using my linux swap partition (on an extended partition) as
> swap partition for FreeBSD. This works completely straightforwardly...

Interesting.  I just confirmed on FBSD-current -- no disklabel is needed
to use a linux swap partition:

#swapon /dev/ad0s8
#swapinfo
Device          1K-blocks     Used    Avail Capacity
/dev/ad1s8b        257040        0   257040     0%
/dev/ad0s8         530112        0   530112     0%
Total              787152        0   787152     0%

(Ooops, I just noticed that my usual swap partition is too small by half 
on this FBSD installation.)

> By the way, i have seen concrete reports that one can install FreeBSD
> completely on logical partitions (that is even /boot/loader supports that),
. ..

FBSD is very happy to run from an extended partition:
#mount
/dev/ad1s8a on / (ufs, NFS exported, local, soft-updates)

That's how I'm posting this reply from FBSD :o)

However, I can't confirm that FBSD's /boot/loader will properly load
the FBSD kernel from an extended partition -- I just tried it again
and it failed, as it always has.

However, the FBSD /boot/loader is trivial to fix:  just copy our
/usr/src/sys/boot/i386/libi386/biosdisk.c over to FBSD and then
you *can* use it to boot FBSD from an extended partition.

I boot FBSD using the DragonFly /boot/loader and everything works
perfectly.  I contacted the FBSD developers just after we fixed
the /boot/loader code, but my suggestion was dismissed as a trivial
and unimportant problem -- so I gave up.  It's no longer my problem.