[syslinux] Booting ISO images over PXE

Andreas Kotes count-linux at flatline.de
Tue Oct 2 12:36:52 PDT 2007

Hi Peter,

* H. Peter Anvin <hpa at zytor.com> [20071002 21:19]:
> > Another idea I had once was some something along the lines of memdisk
> > installing something like a fake MSCDEX driver which uses the TCP/IP
> > stack left over from PXE to fetch the block requested from the CD-ROM
> > over the network ... most of the CD-ROM-drivers I know fail when they
> > encounter another driver already using the MSCDEX-name they're trying to
> > register themselves as - but DOS continues to boot, so the MSCDEX.EXE
> > might be able to use the fake CD-ROM .. you might run into memory
> > problems later on, and e.g. TFTP doesn't support requesting specific
> > blocks, so you'd have to implement something else (block ranges via
> > HTTP, for example, but you might have more luck extenting tftp-hpa, so
> > you don't need to do TCP and be really networking-interactive) ..
> > 
> > .. maybe feasible, but wouldn't help with linux images, or anything else
> > which doesn't use the (rather aged) MSCDEX ..
> > 
> It's not really MSCDEX that's the issue, it's the underlying .SYS 
> (MSCDEX talks to a DOS device driver.)  If this is ELTORITO.SYS you're 
> okay, but El Torito didn't become common until much later.  However, I 
> think it's available with FreeDOS, for example.

I was thinking about getting the fake DOS device driver hooked into the
system by memdisk before DOS is started up, i.e. the driver already
being present when DOS tries to load the 'real' one ..

Unless the corresponding structures are wiped on booting, this might
stand a chance?



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