Date: Mon, 8 Mar 1999 23:03:46 +0200 (SAT) From: Robert Nordier <rnordier@nordier.com> To: mrspock@esfm.ipn.mx (Eduardo Viruena Silva) Cc: hacker@freebsd.org Subject: Re: starting partition Message-ID: <199903082103.XAA17977@ceia.nordier.com> In-Reply-To: <Pine.BSF.4.05.9903081304550.10829-100000@Michelle.esfm.ipn.mx> from Eduardo Viruena Silva at "Mar 8, 99 01:24:05 pm"
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Eduardo Viruena Silva wrote:
> Hello there!
>
> I think this is not a question but an observation...
>
> I have asked you about a problem that occurres when you install FreeBSD in
> two different PARTITIONS of the same IDE disk. It seems to me that
> FreeBSD does not let you do that, I mean, you cannot have version 2.2.8
> and version 3.0 in the same disk because the installation process destroys
> one of the disk labels. (I made a question about it some weeks ago,
> they answered me that I have made a mess with my disk labels, so I
> repeated the experiment and it happened again... I installed version 2.2.8
> in partition 1, and version 3.0 in partition 2. Patition 2 became a
> mess).
BTW: You seem to be using partitions and slices in the SVR4 sense,
where "partition" is what you create with fdisk, and "slice" is a
subdivision of a partition. FreeBSD uses these two terms in an
exactly opposite sense (partitions go inside slices). Just to keep
things confusing, I'll use the FreeBSD terminology below. :)
I sometimes install up to four versions of FreeBSD on the same disk.
However I would usually make it seem to sysinstall that no FreeBSD
slices already exist, by changing the slice type from 0xa5 to
something else (say 0x42 or 0x69) before each install.
The reason for doing this is that support for multiple FreeBSD
slices per disk is something of an "at own risk" option rather than
a fully-recommended way of doing things.
Once all the installation is done, the slices types can be changed
back to 0xa5.
> Some other Unix versions (the old ultrix and osf/1) require three
> "coordinates" for specifying the kernel's position: the disk number, the
> patition number, and the slice letter.
>
> So, if you want to start from disk 2, patition 1, slice a,
> the loader should have to receive:
>
> wd(2,1,a)kernel
>
> and not:
> wd(2,a)kernel
>
> But this is not possbile in FreeBSD loader.
From the 3.1 release (and a bit earlier in -stable), it is possible
to specify
wd(2,1,a)kernel
at the "boot:" prompt. It is also possible to specify the slice
at the /boot/loader prompt (the new /boot/loader being an added
third stage to the bootstrap) using syntax like "disk2s1a".
If you use a boot manager like BootEasy (or the FreeBSD boot0
workalike) which sets the selected slice as active, the new
3.1R boot code will automatically boot from the slice you
select. So it should be as simple as pressing F1 or F2, say.
You can use the 3.1R boot code to boot prior versions of FreeBSD.
--
Robert Nordier
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