Preboot Environment

What is a PE?

Windows Preinstallation Environment is a lightweight system, less than 300Mo for the disk image. When we boot a WinPE, we only have a cmd console and we can do all necessary think to install a computer.

How can create a WinPE image

Vanilla version

Get it from CDROM

Explode the windows cdrom/iso (server or desktop), and get some boot files, you can find it in the sources and bootdirectory.

The boot.wim file is the only file we need to boot a valid winpe system, and /boot/boot.sdi and /bootmgr

How to create boot image

We can create a usb boot device, but i want a netboot winpe system. So we need to create a boot disk image loadable by gPXE.

The Steps are:

• format an usb drive
• add the boot.wim file
• create a bootable windows 7 compliant disk
• create a image disk

Get a Usb drive (512Mo not more than 512), or create a partition with a size of 512M, add the boot.wim file in this paritition. add the boot sector, and dump this disk to an image disk.

modus operandi

On Linux:

mkfs.ntfs -f -L WinPE /dev/sdb1

mount /dev/sdb1 /mnt

cp /data/Windows/boot.wim /data/Windows/bootmgr /data/Windows/boot.sdi /mnt

mkdir /mnt/BCD

umount /mnt

On Windows, if we consider b: as the drive of the usb disk:

bcdedit /store b:\boot\BCD /set {bootmgr} timeout 5

bcdedit /store b:\boot\BCD /create {ramdiskoptions}

bcdedit /store b:\boot\BCD /set {ramdiskoptions} ramdisksdidevice boot

bcdedit /store b:\boot\BCD /set {ramdiskoptions} ramdisksdipath \boot\boot.sdi

for /f "tokens=3" %a in ('bcdedit /store b:\boot\BCD /create /d "Boot Windows PE" /application OSLOADER') do set GUID=%a

bcdedit /store b:\boot\BCD /set %GUID% device ramdisk=[boot]\boot.wim,{ramdiskoptions}

bcdedit /store b:\boot\BCD /set %GUID% osdevice ramdisk=[boot]\boot.wim,{ramdiskoptions}

bcdedit /store b:\boot\BCD /set %GUID% systemroot \windows

bcdedit /store b:\boot\BCD /set %GUID% detecthal yes

bcdedit /store b:\boot\BCD /set %GUID% winpe yes

bcdedit /store c:\boot\BCD /ems {default} on

bcdedit /store c:\boot\BCD /bootems {bootmgr} on

bcdedit /store b:\boot\BCD /displayorder %GUID% /addlast

Now we have a usb drive for booting WinPE system, we can make a winpe.img now.

On linux again:

dd if=/dev/sdb1 of=/data/Windows/winpe.img bs=1024k

gzip winpe.img

Now we have the winpe image we describe in basis gPXE setup, but gzip the file memdisk can gunzip it on the fly.

Custom version

How to modify

Now, for customing this system, we can modify or change the boot.wim file.

For doing this the steps are:

• mount the winpe.img file
• add/remove/modify the boot.wim file
• unmount and save the winpe.img

Modus operandi

This part can be done on linux, we mount a loop device at osfset 65536.

losetup -o 65536 /dev/loop0 /data/Windows/winpe.img

mount -o loop /dev/loop0 /mnt

cp /data/windows/NewWinPe.wim /mnt/boot/wim

umount /mnt

losetup -d /dev/loop/0

How to modify the boot.wim file

For doing this we must have WAIK2 system. We talk about that later.