[syslinux] Memdisk + Freedos problem

Tue Mar 24 15:51:40 PDT 2009

It is solved now with the help of Erwan.

When using the 'raw' parameter of memdisk, it works.

Request to change point d) in the memdisk documentation:

===========================================================================
d) MEMDISK normally uses the BIOS "INT 15h mover" API to access high
   memory.  This is well-behaved with extended memory managers which load
   later.  Unfortunately it appears that the "DOS boot disk" from
   WinME/XP *deliberately* crash the system when this API is invoked.
   The following command-line options tells MEMDISK to enter protected
   mode directly, whenever possible:

   raw        Use raw access to protected mode memory.

   bigraw    Use raw access to protected mode memory, and leave the
        CPU in "big real" mode afterwards.

   int        Use plain INT 15h access to protected memory.  This assumes
           that anything which hooks INT 15h knows what it is doing.

   safeint    Use INT 15h access to protected memory, but invoke
        INT 15h the way it was *before* MEMDISK was loaded.
        This is the default since version 3.73.
============================================================================

It doesn't mention that an image can work perfectly on one PC without additional
memdisk parameters, while you need them (e.g.: raw) on another PC.

Gert Hulselmans

----- Original Message ----
From: Kim Mik <kimmik999999 at yahoo.co.uk>
To: syslinux at zytor.com
Sent: Monday, 23 March, 2009 19:15:10
Subject: [syslinux] Memdisk + Freedos problem

I and some other people have problems with running the freedos image included in
Ultimate Boot CD (UBCD), when using memdisk for floppy emulation.

Memdisk starts booting the image and freedos shows the following menu:

0 Boot Clean
1 Boot UMBPCI (silent)
2 Boot UMBPCI (optimal)
3 Boot UMBPCI (semi-defensive)
4 Boot EMM386 (optimal)
5 Boot EMM386 (semi-defensive)
6 Boot no UMB (defensive)
7 Boot no UMB (ultra-defensive)

0 Boot Clean
____________

  Works fine.

1 Boot UMBPCI (silent)
____________________

  It prints:

==========================================================
FreeDOS HIMEM64 3.26 [Aug 25 2006] (c) 1995, Till Gerken 2001-2005 tom ehlert
HIMEM - Fast A20 method used
UMBPCI c't 11/95 - Siering/Schäpers/Stiller
V3.77 - support for new chipsets, Inter PPro, AMD K7 - Uwe Sieler 08/2008
AMD K8 CPU found
Using CF00-E2FF
Using E700-E7FF
Program installed
LowDMA (haftman# software 11/01): installed
Kernel: allocated 34 Diskbuffers = 18088 Bytes in HMA
Invalid Opcode at 5281 FFFF 0286 E0A0 0000 0000 0000 0000 E0A0 0000 017C 0000 0D86
==========================================================

Then it halts.

2 Boot UMBPCI (optimal)
______________________

  It prints:

==========================================================
FreeDOS HIMEM64 3.26 [Aug 25 2006] (c) 1995, Till Gerken 2001-2005 tom ehlert
HIMEM - Fast A20 method used
UMBPCI c't 11/95 - Siering/Schäpers/Stiller
V3.77 - support for new chipsets, Inter PPro, AMD K7 - Uwe Sieler 08/2008
AMD K8 CPU found
Using CF00-E2FF
Using E700-E7FF
Program installed
LowDMA (haftman# software 11/01): installed
Kernel: allocated 34 Diskbuffers = 18088 Bytes in HMA
Invalid Opcode at 5281 FFFF 0286 E0A0 0000 0000 0000 0000 E0A0 0000 017C 0000 0D86
==========================================================

Then it halts.

3 Boot UMBPCI (semi-defensive)
_____________________________

  Works fine.

4 Boot EMM386 (optimal)
_______________________

  Works fine.

5 Boot EMM386 (semi-defensive)
______________________________

  Hangs at loading CD-ROM driver (no Invalid Opcode)
  If you skip the loading of the CD-ROM driver, it works fine.

6 Boot no UMB (defensive)
________________________

  It prints:

==========================================================
FreeDOS HIMEM64 3.26 [Aug 25 2006] (c) 1995, Till Gerken 2001-2005 tom ehlert
HIMEM - Fast A20 method used
Kernel: allocated 34 Diskbuffers = 18088 Bytes in HMA
Invalid Opcode at 4B51 FFFF 0206 0336 E898 9C8C D285 0475 C085 0374 C031 B8C3 00FF
==========================================================

7 Boot no UMB (ultra-defensive)
_____________________________

  Works fine.

The strange thing is, if I use grub4dos floppy emulation instead of sylinux/isolinux + memdisk
all entries work.

Syslinux/isolinux + memdisk + freedos image work in a virtual machine. Only on my real PC and
some other PCs, it doesn't work, while it does work perfect on some PCs also.

http://www.ultimatebootcd.com/forums/viewtopic.php?t=1635
http://www.ultimatebootcd.com/forums/viewtopic..php?t=1829&highlight=invalid+opcode
http://www.ultimatebootcd.com/forums/viewtopic.php?t=1545&highlight=invalid+opcode

Freedos image for UBCD download link:
http://ubcd.partedmagic.com/downloads/fdubcd/r133/fdubcd.igz

Freedos image for UBCD 'homepage':
http://www.ultimatebootcd.com/forums/viewtopic.php?t=1422

You can also download the whole UBCD50b12.iso, if you want:
http://www.ultimatebootcd.com/forums/viewtopic.php?t=1814

Gert Hulselmans

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