pfSense

I just found the workaround,
Boot the livecd completely, then symlink /dev/gm0, gm0s1, gm0s1{a..z} to their /dev/mirror/gm... equivalents.
Then do the menu 99 install. It will complete and even the fstab and all will be fine.

It's been a while since I tried a gmirror install, but is that still necessary if you kldload all of the gmirror/geom klds before invoking the installer?

On my full FreeBSD install to a gmirror that I have handy, the links in /dev/mirror/ are used and work fine.

I did not load anything extra. I was expecting the livecd to load all the modules as it recognizes the mirror disks.
I did notice that some commands in the installer look for /dev/mirror/gm0 and some for /dev/gm0.

It still may be worth loading all of the geom* modules to see if that makes the /dev/mirror shortcut appear when it didn't before. If it does, we can pre-load that module on the CD and it should all just work.

I will probably do a reinstall in a few minutes. So ill try and report back.
But please note that the problem is the other way around. The /dev/mirror/gm0 devices are always there, the /dev/gm0 is missing.
And that is what the installer is looking for.

Just reinstalled, but i could not find any loadable geom modules, just some .so files in /lib/geom.
It seems that only the commands that test for the existence of the device (which should fix the problem automatically, except for the fact that MAKEDEV is not included on the live disks) and the mount command use the /dev/gm0.

So i guess our best bet is to change the installer commands or add the MAKEDEV script again.