[nycbug-talk] FreeBSD 32-bit to 64-bit?

John Baldwin jhb at freebsd.org
Wed Dec 23 16:15:28 EST 2009

On Wednesday 23 December 2009 3:10:05 pm Charles Sprickman wrote:
> Howdy,
> Anyone got some pointers on how to "convert" an existing 8.0 32 bit 
> install to a 64 bit install?
> Caveat: The machine in question has no floppy, no optical drive, and usb 
> keys and such are a bit wonky on it, so I have to do this without 
> resorting to booting new install media.  I do have a serial console.
> I did manage to build and boot a 64 bit kernel using this incantation:
> make -j4 TARGET_ARCH=amd64 buildworld buildkernel KERNCONF=BWAY8-64
> Installing was rough, the build system wants that installed anywhere but 
> "/boot", so I had to set DESTDIR to a directory in /tmp and move the 
> kernel into place manually.  Using nextboot to boot that kernel works, but 
> the build system seems to kind of fall apart when trying to install world.
> Even simple pointers like "this is how the build system figures out what 
> architecture it's on and these are the variables it sets" would be very 
> helpful.

One tactic I know some people have used to do this is to newfs a swap 
partition, do an installworld into that and boot into single-user with that 
mounted as your / (by editing /etc/fstab or setting vfs.mountroot_from in the 
loader), mount the rest of your partitions under /mnt or some such, 
installworld into /mnt, restore /etc/fstab if necessary, then reboot back to 
your normal layout.

John Baldwin

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