Wednesday, 14 May 2014

E2B - MBR and UEFI booting of large All-In-One Windows Installers

For details about booting to Clover from grub4dos see here.

I was asked recently if it was possible to multiboot large >4GB All-in-One Windows installer ISOs using Easy2Boot in both MBR and UEFI mode.

After some work, I can now answer 'Yes - as long as you use a USB Hard disk for E2B'! - or a USB Flash drive of the 'Fixed Disk' type.

Note: Simone in the Comments below suggests splitting the install.wim file. If this is done with Win 8, you will need to add a special ei.cfg file too, in order to prevent a Microsoft 'licence' error (read the Comments for this blog post for details).

It has always been possible to directly use a AIO ISO on an NTFS-formatted E2B drive for normal MBR-type installs; the problem comes with UEFI installs. UEFI firmware can only boot from FAT filesystems and FAT32 has a 4GB file size limitation. If the Install.wim file is larger than 4GB then we have to place it on an NTFS filesystem.

The new procedure to work around this issue uses two partitions.

Partition 1 - FAT32 - contains all Windows Install files except the Install.wim file
Partition 2 - NTFS  - contains the large \sources\Install.wim file.

You must first make both partition images using MakePartImage. The partition 1 FAT32 image file should be given a filename extension of .imgPTNLBAa. The partition 2 NTFS image file should be given an identical filename but with no file extension at all - e.g.


Only the Win8AIO.imgPTNLBAa file will be listed in the Windows menu, but when it is run, the Win8AIO file will be mapped as (hd0,2) and the Win8AIO.imgPTNLBAa file will be mapped as (hd0,0).

In this way, you can boot via MBR or UEFI and install Windows even from an install.wim file larger than 4GB. The latest E2B versions include this feature.

Full step-by-step instructions on how to make the image files are here (scroll down to 'How to add Windows 7/8 installers with >4GB install.wim files').

Some UEFI systems may not like seeing two partitions - please let me know if you try this and what systems you tried it on!