[syslinux] memdisk and booting DOS images

Quinn plattel at tiscali.dk
Sun Mar 6 05:34:05 PST 2005


Hello,

I seemed to have encountered a problem with memdisk that I have seen 
before when I was playing around with USB device booting at one time.

Here's the scenario:  Take fx a image of a PC DOS bootable diskette.
Boot the image via memdisk. This should boot fine if you use the 
built-in motherboard ide controllers (ide0,ide1).

Now install a PCI IDE controller and put one IDE disk on the PCI IDE 
controller.  Boot the PC DOS floppy image via memdisk.
This scenario fails on me - PC DOS just says "Starting PC DOS..." then 
hangs.

As soon as you take away the IDE disk from the PCI IDE controller then 
PC DOS boots fine via memdisk.

If I take PC DOS and boot it directly via the floppy drive, then PC DOS 
boots fine with or without the IDE disk on the PCI IDE controller card.

Try these two scenario's with other DOS'es - you get the following:
MS DOS: nothing at all - just hangs after booting via memdisk. Floppy: 
Boots to command prompt.
Caldera DR DOS: Shows "Starting Caldera DR DOS..." then hangs. Floppy: 
Boots to command prompt.
FreeDOS (Beta 9):

--snip--
 - InitDiskDrive is too large to handle, using only 1st 8 GB
 drive 81 heads 0 sectors 0 , total=0x8a0ef29-33733690
BIOS reported 0 sectors/track, assuming 63!

Invalid Opcode at 9F00 CC00 0006 0000 0007 07C0 0040 9EC0 07AA 018E 07C4 
09FA 9F00
--snip--
Freedos then hangs here.

Here is FreeDOS when booting from diskette:
--snip--
 - InitDisk
FreeCom version 0.82 pl 3ak XMS_Swap [Aug 18 2004 23:00:58]
--snip--
and eventually booting to command prompt.

The problem seems to point to memdisk somehow.  I have tried version 
2.11, 2.13, and 3.07 of the syslinux package - same problem arises 
everytime.

Any suggestions?

Quinn




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