Netboot of FreeDOS- success!

[Dirk Niggemann <dirk-n@dircon.co.uk>]

 Hello,

Just wanted to let people know I have discovered a method of netbooting
FreeDOS using netboot and 
mknbi-dos. It requires a few patches.....
The details:
	0. Use a modified mknbi-dos that does not go ballistic when presented
with invalid data 
		in:
			a) the OEM ID (all NULs by default on FreeDOS)
			b) the FAT name field. (FreeDOS boot disk ships with 
			 	extra offset data in there)
	1. Use a FreeDOS created boot floppy. Right now mknbi-dos has no
support for the _ahem_ interesting boot sector FreeDOS uses. You need
the original bootsector. You also need different ones if you have:
	a) a FAT12 fs
	b) a FAT16 fs (b probably can't work at all right now, 'cause it needs
different adjustments 
  			to cope with different image sizes. FreeDOS stores some DOS sector
offsets in its
		 	boot sector to save on calculations. Check out the source to FreeDOS
sys.com (and
			boot.asm) for the gory details. 
	2. replace the boot sector with one one that 
		a) does an initial 'disk init' (e..g calls int13 with dx=0 on startup)
		b) relocates itself to somewhere at least 4K + 7c00h below top of
memory. (Otherwise, 
			it trashes the ramdisk driver. The correct way to do this would be to
use the 
			'RPL top of memeory adjustment' interrupt but there's no space in the
boot sector
			 for it.) 
		I can provide patches for this.
	3. use a modified kernel version 2011 that includes rudimentary support
for the 
		'RPL top of memory' adjustment function (int 2fh with ax=4a06) to
prevent FreeDOS itself 			relocating on top of the RAM disk driver. I
have modified kernel.asm to do this. 
		Unfortunately, no friendly support fo converting this into a DOS
memory block named 'RPL' 
		or un-install (yet). Patches available to interested parties. 

This is basically very expermental right now, and needs some serious
cleanup. suggestions and helpers welcome.

			
    Dirk Niggemann 
    dirk-n@dircon.co.uk
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