Steve's blog

My second alpha release of a Wheezy netinst CD for amd64 EFI seemed to work OK for me and a few others, but it wasn't 100% good, with (at least) two issues:

It didn't work as a hybrid (CD or USB) image, just working from CD for EFI
It didn't work for BIOS booting due to a silly bug

In the couple of days since then, I've fixed both of these issues. Yay! Hybrid boot was easier than I expected - I've just added a tiny FAT partition to the image containing the grub EFI bootloader and that seems to work fine. I also found that I made a mistake in the ordering of the El Torito boot records in the last image. BIOS boot seems to be limited to just the first image available on the machines I've tested with, wherease EFI will happily work as a secondary image. I've swapped them around in my code, and things look much better now. So, time for another CD alpha release for testing.

Grab the image from http://cdimage.debian.org/cdimage/unofficial/efi-development/upload3/ if you'd like to help test it. Please do, and let me know via debian-boot/debian-cd how you get on.

As previously, the "bits" subdirectory contains all the tweaked d-i packages I've played with, in both source and binary form. My debian-cd changes are still in my branch but are just about ready for merging I think. I've posted my full set of d-i patches to the debian-boot list for review now, and hopefully we'll be able to get those changes merged in after the Wheezy d-i beta 2 build is done. Full speed ahead for EFI in beta 3!

03:16 :: # :: /debian/CDs :: 16 comments

Comments

Possibility of grub-less EFI stub booting?
xlz wrote on Thu, 30 Aug 2012 16:25

"It seems that EFI has most of the features of GRUB and 90% of what is truly needed to direct boot a Linux kernel. "[1] Even the kernel is moving stuff that belonged to grub into itself.[2] So one might suggest why not boot with EFI stub to completely get rid of the grub duplication? Heck, I don't even need GPT for my poor hard drive with no more than three partitions.

Actually I'm doing such thing and it works perfectly, manually converting a BIOS installed Debian into EFI based with the method in [3]. Here is my dirty homebrew script[4] for this, ugly but you get the idea. I wonder it won't take too much effort to make it work with existing initramfs-tools infrastructure, but I know nothing now.

Matthew Garrett does have valid objections in [1]. He seems to be over-concerned about the incompetence and inconsistency of UEFI firmware as he has been personally burnt out by that, I guess. My point is that the grub-less EFI stub booting should be at least one viable option for cetain niche of users who prefer lightweight and speed and can work with somewhat inconsistent UEFI boot manager UI, while adding support for it probably won't destabilize the system or other existing tools.

By the way, debian-wheezy-amd64-efi-test3.iso works great on my T520, with a manually partitioned disk (msdos, 200M /boot/efi, /, swap). Thank you for your nice work.

[1]: http://lwn.net/Articles/505823/ [2]: http://lwn.net/Articles/507827/ [3]: http://tanguy.ortolo.eu/blog/article51/ Actually I got here from your comment on that blog. [4]: http://pastebin.com/xGqrw35D

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