Date: Mon, 15 Nov 1999 23:40:25 -0600 (CST) From: Hal Peterson <hrp@alum.mit.edu> To: freebsd-questions@freebsd.org Subject: Selecting the boot slice Message-ID: <14384.59584.964973.326245@melchett.gofast.net>
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For historical reasons, I've configured my drive with four slices:
slice one for DOS; two FreeBSD slices (two and four) with swap, root,
and /var partitions; and a big slice, three, for the FreeBSD /usr
filesystem.
(My FreeBSD software is:
FreeBSD 3.0-RELEASE #11: Sun Aug 1 22:26:51 CDT 1999
hrp@melchett.gofast.net:/usr/src/sys/compile/MELCHETT
)
I can boot DOS from slice one and FreeBSD from slice two, but I
haven't found a way to boot from FreeBSD in slice four. Both BootEasy
and OS-BS prompt correctly for slice four. I ask to boot from slice
four. Every time, I wind up getting the other FreeBSD from slice two.
I poked around in /usr/src/sys/boot/i386/boot2/boot2.c and found that
where it parses the specification for the kernel file, there is an
undocumented parameter for the slice number. The documented syntax in
boot.help is:
Usage: bios_drive:interface(unit,partition)kernel_name options
but boot2 actually parses this:
Usage: bios_drive:interface(unit,slice,partition)kernel_name options
^^^^^
There's at least one additional trick with the slice, which is biased
by BASE_SLICE (2). I tried to specify my slice-four kernel:
0:wd(0,5,a)kernel
and, just in case:
0:wd(0,6,a)kernel
and none of it worked: I always wound up with the system from
/dev/wd0s2a.
So, what's the trick? Is it possible to boot from slice 4? Has
anybody ever tried this? It *ought* to work.
--
Hal Peterson Bloomington, MN, USA
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