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Experimental MEMDISK COMBOOT32 Module

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#1 Sha0


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Posted 08 May 2011 - 03:12 PM

A very cheap hack to make a MEMDISK COMBOOT32 module, so you you can do something like:

boot: memdisk.c32 diskimage.hdd harddisk=1 raw



Which is loosely similar to:

boot: memdisk initrd=diskimage.hdd harddisk=1 raw

Except that you are returned to the Syslinux CLI by the former but not by the latter.

Why might you wish to do this? Probably because you will be following it up with chain.c32:

boot: chain.c32 hd0

Where the above would boot the first hard disk, but you now have diskimage.hdd available as a RAM disk and as the second "hard disk."

Roughly equivalent to the GRUB4DOS:

grub> map --mem /diskimage.hdd (hd1)

grub> map --hook

grub> rootnoverify (hd0)

grub> chainloader +1

grub> boot

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#2 Krokodox



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Posted 15 September 2011 - 01:26 PM

Ohhhhh..... nice!

Can I please ask you to give an example of a menu configuration that can be used via PXE boot? I.e. I now have the following for installing Windows 2003 SP2 via an .ISO image from the network:

LABEL w2k3_cd_inst

  MENU LABEL ^Windows 2003 Std x86 Install from CD


  APPEND iso raw


What I would like to be able to do is to get rid of the .ISO file and instead have the contents of the CD image served via a harddisk image. Why? Well, because I find it to be cumbersome to have to re-create the .ISO file everytime I want to make a small change. It would be much easier to have all setup files in a disk image that I can manipulate via ImDisk instead.

I believe / hope that I have figured out how this can be achieved:

1. nLite a Windows CD to whatever SP and drivers needed
2. Add $OEM$ directory structure and whatnot
3. Copy all this into a pre-made disk image mounted with ImDisk
4. PXE boot a target computer
5. Select a menu with settings for mounting this disk image as the second hard disk AND a small PE or whatever that can start JFX's WinNTSetup v2 (http://www.msfn.org/...-winntsetup-v2/) as the boot harddisk
6. Start the installation and hope for great results :)

Is this doable at all or should I settle for the working but clunky .ISO via PXE / HTTP method? Oh, and before I forget: *a big thank you* for the excellent WinVBlock driver! :good:

Edited by Krokodox, 15 September 2011 - 01:27 PM.

#3 nando4


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Posted 16 September 2011 - 01:01 PM

Where the above would boot the first hard disk, but you now have diskimage.hdd available as a RAM disk and as the second "hard disk."

Sha0, does this mean the contiguous disk image is directly mapped for direct read/write so changes are saved back to the image? If it is, then is there a way to boot so as to not create the ramdisk image of diskimage.hdd? I believe that process copies the disk image to ramdisk and so slows the bootup, especially in my case where I use a 11MB image file.

#4 geneC



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Posted 16 January 2012 - 02:17 PM

MEMDISK doesn't do memory-mapped files. It does ramdisks which means the entire disk is read at once into memory, used in memory and can be seen as wasting said memory, depending on what you're doing.

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