[syslinux] Re: [fd-dev] Problem with memdisk and Free FDISK

Patrick J. LoPresti patl at users.sourceforge.net
Mon Jul 7 12:00:16 PDT 2003

"Brian E. Reifsnyder" <reifsnyderb at mindspring.com> writes:

> > Browsing the fdisk source code, I suspect I could work around this
> > problem by setting "EMULATE_DISK=1", but since my copy of fdisk.exe
> > does not have debugging enabled, this option is not recognized.
> Nope.  The EMULATE_DISK function only creates a fake simulation of a
> hard disk in the buffers used by Free FDISK.

As long as it makes it skip drive 1 and move on to drive 2, that would
actually be enough.

But it would be a hack, anyhow.  I would much prefer to see Free FDISK
and memdisk play together nicely.

> > Questions:
> >
> >   1) Where can I obtain a copy of fdisk.exe with DEBUG enabled?  (Do I
> >      have to purchase Borland C++ and build it myself?)
> If you would like, I could compile one for you.

If we can get this fixed easily, that will not be necessary...

> My first thought would be that it is in memdisk.  But, I am not
> familiar with PXELINUX.  My guess, from your description, is that
> you are attempting to run Free FDISK from within an emulated DOS
> machine (DOS Emu?  Bochs?).

It is real Microsoft DOS 6.22, but on a virtual disk.  memdisk hooks
the BIOS to create a virtual drive from which you can boot DOS (among
other things).  I use it in my project
(http://unattended.sourceforge.net/) to support booting from CD-ROM
and from the network.

You can download the source from the SYSLINUX home page at

> I suppose that it would be possible to add the capability to
> selectively support interupt 0x13 extensions.  For example, change
> Free FDISK such that you could instruct it to use interrupt 0x13
> extensions with disk 1 but not with disk 2.  I don't think it would
> be too hard to do this.  What do you think?

That would solve my problem.  Although it might be conceptually
simpler to just skip drive 1 entirely when I tell fdisk to operate on
drive 2...

But having these tools work together seamlessly would be even better.


 - Pat

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