[solution] Re-installing Windows *after* FreeBSD

Amarendra Godbole amarendra.godbole at gmail.com
Thu Apr 19 02:19:18 UTC 2007


I recently came across a problem where I had to re-install Windows XP
on my laptop, which already had FreeBSD on the second slice. I am sure
many must have faced this issue, and hence I am posting this solution
that I adopted to re-install Windows (okay, here I already have two
slices, first for Windows and second for FreeBSD).

Typical disk setup: 40G HDD on Dell Latitude D400 laptop. First slice
(partition on Windows parlance) of 15G and second slice of 25G for

Pre-condition: Windows slice already exists. This procedure typically
applies to re-installing Windows.

1. Re-install Windows in a normal way, making sure you don't touch the
FreeBSD slice of the machine. Since Win does not honor the MBR, it
will install its own MBR after the installation, thus hiding FreeBSD.
2. After step 1., boot the machine from FreeBSD boot CD-ROM (CD 1) of
your release. Mine is FreeBSD 6.2-RELEASE
3. In sysinstall, go to the Fixit mode, and select the option for
"live" FreeBSD system. You will now get a prompt something like:
4. Run the following command:
    boot0cfg -B ad0
    This command re-installs the boot0 boot manager on disk ad0. It
will properly detect both OSes', and re-install the MBR appropriately.
5. Reboot. You will now be greeted with the very famous prompts:
F2 FreeBSD

Hope this helps. Similar thing (re-installing grub) can be done for
Windows and Linux dual-boot, when Win kicks off grub.


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