Have no hope already! UEFI system.

[srs5694]

Maybe that is something unique in Windows 7 Enterprise, because I formatted the disk many times and I checked before I installed ubuntu and the filesystem of the ESP was always FAT16, and till now Windows boots fine in FAT16.

It's certainly possible that it varies from one variety of Windows to another. It's also conceivable that the installer just has problems with certain sub-types of FAT16. I ran into problems with FAT16 partitions created with Linux's mkdosfs, but maybe a FAT16 partition created using a Windows tool would work better. It might even vary with the UEFI implementation, although the UEFI itself had no problems with the FAT16 ESPs that gave Windows fits in my tests. Note also that this is a problem with the Windows 7 installer. Once installed, you can change the ESP from FAT32 to FAT16 or vice-versa and it'll be fine.

I also mentioned that BIOS compatibility mode never worked for me in installations of Windows & Ubuntu, so I support what you say, but in theory, or at least the UEFI specification says that BIOS compatibility can be done.

I'm not saying that a UEFI's BIOS compatibility mode is useless or doesn't work; my point is that a computer booted using that mode acts just like a BIOS computer, not like a UEFI computer. Although at least some boot loaders can switch from UEFI mode to BIOS mode (rEFIt does it on Macs), for the most part the two modes should be considered entirely separate. In particular, there's nothing to be gained from putting EFI boot code in an MBR or PBR; and if you switch to BIOS mode and use regular BIOS-style MBR or PBR code, your computer will boot just like a BIOS computer, with all the limitations that entails (like Windows requiring MBR partitions rather than GPT).

[YesWeCan]

Thanks Avidanborisov & srs5694 for you informative replies.

I guess I thought the new mobo firmware would be highly flexible so you could boot a MBR, boot a PBR or boot a .efi file on a per partition/disk basis as you wished. It sounds a little more like the old and new systems are not integrated.

I am interested in the nature of the .efi files. I wonder whether there is an online programmer's guide?

[sigh]UEFI is written in C? You must be kidding. Gawd, why bother? C is such an old-fashioned, miserable excuse for a programming language. [/sigh]

[srs5694]

I guess I thought the new mobo firmware would be highly flexible so you could boot a MBR, boot a PBR or boot a .efi file on a per partition/disk basis as you wished. It sounds a little more like the old and new systems are not integrated.

I'm not sure how easy it is to switch modes on UEFI-based PCs. On Macs, it can be done in rEFIt; however, once you've chosen the path, you can't pick and choose which aspects of UEFI and which aspects of BIOS you want to use. The OS will see the computer as one or the other, not a mish-mash of both, both during the boot process and once booted.

I am interested in the nature of the .efi files. I wonder whether there is an online programmer's guide?

See http://www.uefi.org/home/. There's lots of documentation there.

[sigh]UEFI is written in C? You must be kidding. Gawd, why bother? C is such an old-fashioned, miserable excuse for a programming language. [/sigh]

You are full of opinions, aren't you? Are you aware that Linux, and most major Linux programs, are written in C? I can understand and respect if you personally don't like C, but please realize that's a personal opinion. Not everybody shares it.