Usage Notes
The goal of this page is to provide answers and details on topics that aren't really suited for the FAQ.
Rufus 2.0 adds the following features:
- Grub 2.0 support (including Grub 2.0 system files)
- Grub4DOS support (including Grub4DOS system files)
- Windows To Go support
- Decompression of
.Z,.gz,.bz2,.xzand.lzmaimage files - additional translations
Considering this, the size increase is actually quite minimal for the amount of new features that were integrated.
Unlike regular ISO → UFD creation, where one can just extract the ISO files, the creation of a Windows To Go drive requires the application of a Windows Image ('sources\install.wim'), which is a completely different process from a regular extraction. Because there is no Open Source library that does WIM image application, we are forced to use the WIM API from Microsoft.
However the Microsoft WIM API requires the `install.wim` image to be accessible as a regular file before it can process (we can't just point the WIM API to the ISO, or part of the ISO that contains the image), which means that, to be able to do that without having first to extract a ~4GB file to a temporary drive (and make sure it gets deleted when we're done with it), we need the capability to mount an ISO as virtual drive, which is something that only Windows 8 offers natively (and of course, there again, there are no Open Source solutions we can use to create a virtual drive). Since Windows 7 and earlier do not provide native ISO mount capabilities, we just can't support these OSes at this stage.
We may add image extraction support for Windows 7 later, but this adds a bit of complexity (creating a 4GB file out of the blue might not suit to well with users who are already low on space), as well as extended delays on a process that is already very time consuming.
Yes.
- If you want _Restricted_ Boot (a.k.a. Secure Boot), you should use GPT for UEFI. This will create a drive that can only be booted on an UEFI computer, in UEFI mode, and that uses a boot chain that should be signed by Microsoft all the way. Note that this mode definitely requires a FIXED USB drive.
- If you want dual BIOS + UEFI boot, you should use MBR for BIOS + UEFI. This mode also allows you to use a REMOVABLE USB drive (though I have had ZERO success booting from REMOVABLE - Only FIXED drives seem to work with Windows To Go).
- If you want to boot in UEFI mode, but don't care about Secure Boot and want minimize the wastage incurred by the MSR and EFI partitions (as well as try your luck with a REMOVABLE UFD), you should use MBR for UEFI.
Due to an antiquated boot process that they are too scared to change (namely hiding stuff in the hope users won't notice it), Microsoft requires every GPT drive that Windows will run from to have an MSR, so we follow suit. Note that Windows installation GPT media don't have this requirement (since they don't run Windows but merely install it). Read more about MSR here.
The UEFI specs hint (but aren't entirely explicit) that a FAT32 partition should be used for FIXED media to boot stuff in EFI mode. And indeed, Windows To Go will not boot on GPT drives unless you installed BCD on a FAT formatted EFI system partition (which should be created without a label!). But then that means you are restricted with the FAT32 minimum partition size, which is tied to the minimum cluster size that you can create a FAT32 FS with which itself is tied to the disk sector size. This means for instance that, for a 4k drive, you must create a ~300MB EFI system partition if you want to be able to format it as FAT32.
Copyright © 2012-2024 Pete Batard
