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Multi-OS Installation: Configuring the Windows Image – Part 2

Continuing from where we left off in Part 1. In the /export/install/images/W51AA directory there are several directories: boot, i386, inf, amd64, and sys. The directories contain the following:

boot/ – the collection of bootloader files and the sif file.

inf/ – the driver information files. The contents of this dir is read by the python RIS implementation processes.

sys/ – the drivers themselves

i386/ – the cab files and other files found on the i386 directory on the media

amd64/ – on 64 bit OSes, this contains 64b versions of the i386 files.

The boot directory is populated as follows. Modifications need to be made to the actual windows binaries using your binary editor of choice. There are several strings, such as “winnt”, prevalent throughout all of the binaries and they each need to be replaced with a new string. This is done to create uniqueness across all of the windows install variants all of which request the same files such as winnt.sif, ntdetect.com, and whatnot. Using your binary or hex editor of choice, and substitute the following strings:

  • startrom.n12 – NTDLR to w50aa
    • rename this file to w50aa.0
  • setupldr.exe – winnt.sif to w50aa.sif; ntdetect to ntdw50aa;
    • rename this file to w50aa
  • ntdetect.com – no string replacement
    • rename this file to ntw50aa.com

Alternatively, the following script snippet can be adopted to use. In the example below let ${Lwhich}=”w50aa”. The full script can be found at https://www.karlmajer.com/files/addnewos/addnewos.sh. Note, if using the script, the script assumes you’ve created the directory w50aa/i386 and/or w50aa/amd64 depending on the bitness of the OS and copied the files from the install media to those locations.

echo “Preparing boot directory.”
echo “…cabextracting files…”
cabextract -d boot/ i386/startrom.n1_
cabextract -d boot/ i386/setupldr.ex_

echo “…copying files…”
cp i386/ntdetect.com boot/

echo “…editing binaries…”
echo “…..startrom.n12…”

cat > /tmp/${Lwhich}.startrom.$$ << EOF
:%s/NTLDR/${Lwhich}/g
:wq!
EOF
vim -b -s /tmp/${Lwhich}.startrom.$$ boot/startrom.n12

echo “…..setupldr.exe…”

cat > /tmp/${Lwhich}.setupldr.$$ << EOF
:%s/winnt.sif/${Lwhich}.sif/g
:%s/ntdetect/ntd${Lwhich}/g
:wq!
EOF
vim -b -s /tmp/$Lwhich.setupldr.$$ boot/setupldr.exe

echo “…renaming binaries…”
mv boot/ntdetect.com boot/ntd${Lwhich}.com
mv boot/setupldr.exe boot/${Lwhich}
mv boot/startrom.n12 boot/${Lwhich}.0

You’ll note the vim is being used in binary mode (-b) in order to do the edits. The stubfiles simply create regex expressions for vim that are used to handle the search and replace. The script also handles the renames for you as well.

When it is all said and done, you will have the following files in the boot directory: w50aa, w50aa.0, and ntdw50aa.com. If you’re using the full version of the script then a w50aa.sif configuration file will have been created also. Those files map to the old ntldr, ntdetect, and then the setup specific files, setupldr.exe and the winnt.sif file.

To populate the i386 directory all that is required is to copy the i386 directory off the media directly into the tree.

For the inf and sys directories, the following needs to be done. Note that ${BIT} denotes 32 or 64 bit and pulls files from the appropriate directories accordingly. Again, this is included in the script linked above.

echo “Preparing inf and sys directories.”

if [ ${BIT} ];
then
echo “…extracting inf files…”
cabextract -d inf amd64/[Nn][Ee][Tt]*.[Ii][Nn]_
echo “…extracting sys files…”
cabextract -d sys -F *.sys amd64/driver.cab
else
echo “…extracting inf files…”
cabextract -d inf i386/[Nn][Ee][Tt]*.[Ii][Nn]_
echo “…extracting sys files…”
cabextract -d sys -F *.sys i386/driver.cab
fi

echo “Complete.”

That takes care of the directories. The only remaining things to do are to update the tftpd.map file and to create a few symlinks to fix bizarre windows naming conventions as well as update the windirs.conf which is the binl parser configuration file and update it to include this new OS we’ve added. Both of these are covered in detail in the script.

That concludes the preparation of the windows image. The next section will discuss setting up the low level boot and PXE environment.

>>> Karl

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