Booting FreeDOS from logical partition

I saw this posted on the mailing list, and I am reposting it here because others may have a need to install FreeDOS on a logical partition and boot from there:

Chris Hodapp writes:

I asked a little while ago if FreeDOS would run off of a logical drive in an extended partition (I'm trying to conserve primary partitions wherever possible because I'm doing some _MAJOR_ multi-OSing. I try to run each system, first of all, off of a loopback filesystem on a FAT drive. If that doesn't work (not many OSes like it) then I try and run it off of a logical drive in the extended partition table. Many OSes do this without even being supposed to.)

And you told me no, it wouldn't run, compatibility issues and all that.

Knowing me, you'd know that I just HAD to try and run it off of a logical drive anyway.

So, I made another logical drive (I think I'm up to hda11 or hda12 in Linux notation), it was as small as possible... about a 3 MB FAT12 partition. I booted from a FreeDOS floppy and SYSed everything to it. I had tried this on a previous version, and it went NUTS. Like, "thereisnowayinhellthatiwilleverloadsystemfilesonthatpartition" nuts. And this time it worked fine. Maybe last time I was using another primary partition...

Like I might have been saying, SYS worked fine on the second DOS partition. I added an entry to my boot manager (XOSL... love it) and gave it a try. To my surprise again, it booted right up. Then it started loading the CONFIG.SYS and AUTOEXEC.BAT files from my first drive, and you can figure out what happened if you read the message that I posted a day or two ago about QEMM and how much FreeDOS hated it.

So I guess it runs off a logical drive without much trouble. What I usually get when I try and run DOS versions off of a partition other than the first is that it searches the first drive, rather than the boot drive, for all the system files, and goes nuts when it can't find them. Caldera DR-DOS (what I've mostly been using) doesn't seem to care... and, apparently, neither does FreeDOS. Now if I can just figure out how to make it use the AUTOEXEC.BAT and CONFIG.SYS on the second drive rather than the first... I think I may have dug up some util once that could tell you which drive you booted from, and I think I've got a device driver you can put in CONFIG.SYS and it will chain any file you specify onto the end of the copy of CONFIG.SYS that is in memory.