/boot on a separate partition
glenn at antimatter.net
Tue Jul 19 02:23:15 GMT 2005
At 06:13 PM 7/18/2005, Ross Kendall Axe wrote:
>-----BEGIN PGP SIGNED MESSAGE-----
>Luke Dean wrote:
> > On Mon, 18 Jul 2005, Ross Kendall Axe wrote:
> >> I am currently trying to get to grips with FreeBSD and am trying it out
> >> on an old Pentium machine. However, the machine's BIOS can't seem to
> >> read past 504MB, so I want to place the /boot directory in a small 25MB
> >> partition at the start of the drive. Setting up the partition with
> >> sysinstall is easy enough, but does anyone have any suggestions of how
> >> to diddle the bootloader to accept this configuration?
> > All I would expect you have to do is use FDISK to make two partitions,
> > remembering to mark the first one as bootable. Then use disklabel to
> > create your slices. Make a /boot slice on the first partition, then
> > make a / slice and a swap slice on the second partition.
> > That should be all that's required for what you're trying to do.
> > A little over a year ago, I had to split up a drive to solve the same
> > problem you're having, but I went the "small /" route instead, so you
> > might be running into a problem I didn't have.
> > Luke Dean
>I created the partitions easily enough when installing the system. I
>created a single slice and, inside that, partition d as my small /boot
>partition and partition a as the root.
>The problem I'm having is trying to actually boot the system. On boot,
>the output (after the BIOS) looks like this:
>error 1 lba 1190783
>boot: <short delay...>
>The 'error 1' is presumably due to my dodgy BIOS, and 'No /boot/loader'
>happens because it's looking on the wrong place for the stage 3 loader.
> Undaunted, I type 'ad(0,d)/loader' to load the stage 3 loader. The
>loader appears to load properly, apart from the fact that is displays
>the message "can't load 'kernel". At this point, I type 'boot
>kernel/kernel', which successfully loads the kernel and produces a
>momentary 'twirling baton'. The keyboard then resets and the system hangs.
>Attempt 2: Change all occurrences of /boot/ in all text files in the
>/boot directory to /. Then, at the stage 3 loader prompt, type 'include
>/loader.rc' instead of 'boot /kernel/kernel'. Again, the kernel appears
>to be loaded successfully, and I get the standard boot menu with the
>ASCII beastie. However, the boot hangs as before, with a keyboard reset.
>Attempt 3: Try to load the kernel directly from stage 2 by typing
>'ad(0.d)/kernel/kernel'. Fails with a register dump and the message
>It's starting to look to me as though the stage 2 bootloader and kernel
>both want to be in the /boot directory on partition a. I'd love to be
>proved wrong :-)
I think this is exactly the case.
According to the boot(8) man page, you can create a /boot.config that will
allow you to customize things. The only catch being that /boot.config has
to be on the a partition of the slice you are booting from. Normally the a
partition would be / and also contain /boot.
/ defaults to being 256MB. If you're trying to conserve space, it might be
easier to run through an install and see how big / really needs to be and
then do a second install and customize the size of / so that it only has
the space it really needs. (On one of my 5.4 systems / requires about 53MB)
You may have problems later on if you make the size of / too small.
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