[syslinux] unloading memdisk

[Joachim Bass]

Hi Peter,

I'm using isolinux and memdisk to create a multiboot rescue cd for
personal use as described on Bart's page (www.nu2.nu). One boot item
is to boot DOS 7.1 from Win98SE with a lot of other staff for emergencies.
This DOS bootimage puts all necessary stuff into it's own ramdisk (XMSDSK).
Some progs on the ramdisk needs access to floppy drive A: and unfortunately
I've no chance to modify this behavior because I've only the Exes.
While memdisk use A: the real floppy is assigned to B: and that is my
problem.
So I've read all docs and searched through the whole mailing list in the
hope
to find a solution.
In the mailing list I've found the following thread (see below).

So, if I cut express a wish it would be a great complaisant if you could add
a function to disable memdisk so that it releases floppy drive A:

In the new release 2.08 you have add the sample prog mdiskchk to check for
memdisk. Perhaps you can extend this prog with a /u or -u switch to unload
the
memdisk?

Regards
Joachim




>Bernd.von.Osten at bccomponents.com Bernd.von.Osten at bccomponents.com 
>Thu, 29 Aug 2002 08:34:22 +0200
>
>Hi SysLinux,
>i'm using pxelinux.0 and memdisk to successfully boot dos on my PXE capable
>workstation.
>But aber the DOS boot I need to get access to Drive A: again. My DOS
>bootimage is putting all necessary stuff into it's own RAMdisk.
>How can I disable memdisk, so that it releases drive A: (does not
>necessarily free the allocated memory for it's RAMdisk ..)
>
>with kind regards / mit freundlichen Grüßen
>
>Bernd von Osten
>
>
>H. Peter Anvin hpa at zytor.com 
>Wed, 28 Aug 2002 23:43:17 -0700
>
>Bernd.von.Osten at bccomponents.com wrote:
>> Hi SysLinux,
>> i'm using pxelinux.0 and memdisk to successfully boot dos on my PXE
capable
>> workstation.
>> But aber the DOS boot I need to get access to Drive A: again. My DOS
>> bootimage is putting all necessary stuff into it's own RAMdisk.
>> How can I disable memdisk, so that it releases drive A: (does not
>> necessarily free the allocated memory for it's RAMdisk ..)
>> 
>
>This is currently not supported.  It wouldn't be too hard to add, 
>though, so I might do that.
>
>Note that you can access your floppy drive as B: when MEMDISK is loaded.
>
>	-hpa
>
>
>H. Peter Anvin hpa at zytor.com 
>Thu, 29 Aug 2002 00:25:32 -0700 
>
>Bernd.von.Osten at bccomponents.com wrote:
>> 
>> BWLOADHI has a "bwloadhi /u" option, which uses an additional int13h
>> function to trigger the unload procedure. Maybe this can be implemented
in
>> Memdisk as well?
>> 
>
>Something like that would work.
>
>> At the moment I'm thinking about a quick and dirty test program (IMDL -
>> IsMemDiskLoaded), which detects the presense on Memdisk in the
workstations
>> memory but looking for magic strings in Memory
>> (like:
>> "MEMDISK " VERSION " " DATE;
>> const char copyright[] =
>> "Copyright " FIRSTYEAR "-" COPYYEAR " H. Peter Anvin";
>>  )
>
>Unfortunately doesn't work -- that's in the setup code, which is not 
>retained.
>
>> Then I can react on that issue correctly in my batch file within dos and
>> ignore the presence test of the bootmedia in the boot drive.
>
>The easiest thing to do, if this is possible, is to put a well-known 
>volume label on the MEMDISK image and look for that.  I don't know if 
>that's what you want to do, though.
>
>	-hpa

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