UEFI and Linux

[Meneer Jansen]

UEFI is the successor of BIOS. At least, that all I understand of it... Dunno what 'secure boot' is. But there is disturbing news about UEFI. Samsung laptops can be bricked by Linux because of UEFI and Lonovo struggles with it too (Phoronix: Lenovo UEFI Only Wants To Boot Windows, RHEL). Gigabyte has troubles too (Phoronix: Gigabyte's ASPM Motherboard Fix: Use Windows).

My question is: can I safely buy a motherboard w/ UEFI in general? Officially one should be able to turn it off in favor of BIOS. Does every motherboard now-a-days have UEFI? For instance, I'm thinking of buying this MoBo, but I don't understand the BIOS specs (see below). Does it have UEFI and can it be turned off?

- 64Mb AMI UEFI Legal BIOS with GUI support
- Supports "Plug and Play"
- ACPI 1.1 Compliance Wake Up Events
- Supports jumperfree
- SMBIOS 2.3.1 Support
- CPU Core, IGPU, DRAM, 1.8V PLL, VTT, VCCSA Voltage Multi-adjustment

[Kano]

Asrock has an interesting UEFI implementation. It is not really standard conform as you can enable even Secure Boot when CSM (which you find in the AHCI settings) is still active. CSM is basically BIOS emulation. It also has got an integrated update tool which can directly connect to internet and download and install latest firmware - you don't have to download it manually. You should reset the system to setup defaults after every update.

[Meneer Jansen]

Asrock has an interesting UEFI implementation. It is not really standard conform as you can enable even Secure Boot when CSM (which you find in the AHCI settings) is still active. CSM is basically BIOS emulation. It also has got an integrated update tool which can directly connect to internet and download and install latest firmware - you don't have to download it manually. You should reset the system to setup defaults after every update.

So I take it that Asus MoBo's work nicely w/ Linux?

[Kano]

Asus has a bug in the UEFI implemention that it removes entries with same filename (-L option to efibootmgr). It only keeps the last entry. As the efi partition is fat you can modify the entries with different upper/lowercase, but it is definitey a bug that Asus does not want to fix - i reported the error but it is no Win error, so no fix.

http://kanotix.com/files/fix/efi/asu...v-uefi-bug.txt

I could test Asrock only 1h or so, did initial secure boot testing, after that i had no access to that board. Basically i knew enough after that time...

[Meneer Jansen]

Asus has a bug in the UEFI implemention that it removes entries with same filename (-L option to efibootmgr). It only keeps the last entry. As the efi partition is fat you can modify the entries with different upper/lowercase, but it is definitely a bug that Asus does not want to fix - i reported the error but it is no Win error, so no fix.

http://kanotix.com/files/fix/efi/asu...v-uefi-bug.txt

I could test Asrock only 1h or so, did initial secure boot testing, after that i had no access to that board. Basically i knew enough after that time...

Sorry, I meant Asrock of course. But I take it from your reply above that Asus and Asrock MoBo's do not work (properly) with Linux anymore if they have UEFI?

[Kano]

Both work with UEFI, there is no current board out there without UEFI anyway (everything else is outdated). If it has a Win 8 logo on the website then Secure Boot (and Fast Boot) is supported as well (I would not buy something else). I just mentioned that I found a bug in the Asus UEFI, it does not mean that it does not work at all, it works just when you want to use direct boot without grub2 or gummiboot with different options for the same kernel you have to modify the name for the loader. Ubuntu really annoys me for direct boot without initrd, they changed one kernel option that you need an initrd just because of 1 user who does not want to compile his own kernel. Of course i can change it back as well but that affects all Ubuntu users who want to boot without initrd (thats even simpler with gpt as you can use root=PARTUUID=xxxx without initrd and more than 1 hd) - with initrd it is usally a bit slower (ok, we speak about 1s or less but still annoying).

https://bugs.launchpad.net/ubuntu/+s...x/+bug/1056563

Back to your question i would most likely use the Asrock board as it is very easy to install firmware updates and it has all needed features. I could not test all aspects in about 1 h however - it was not my board, i just helped to get it running and tested some things.

[Meneer Jansen]

@Kano. Again, thanks for your fast reply. So I take it that most MoBo's work just fine w/ standard Windows 7 (I hate Win8's UI from what I've seen of it) and Linux/Ubuntu dual boot w/ Grub (2)?

Thank you for the tip about the Asrock MoBo. They're usually somewhat cheaper too..

[Kano]

It does not matter if you use Win 7 or Win 8, just when you want to use UEFI dualboot it would be better to install Win 7 SP1 directly - without modification only from DVD possible in UEFI mode - of course you can replace the UEFI loader (efi/boot/bootx64.efi) to use an usb key as well to install. Win 8 does not have got this problem. Usually you see no Win installs with grub 2.00 efi mode in the grub menu, but you can just put this file:

http://kanotix.com/files/fix/efi/custom.cfg

into the /boot/grub directory and they will appear. Win 7 without SP1 has got problems with Intel gfx drivers in UEFI mode, so best update immediately or even better do not use such updated install media.