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Re: [SOLVED] Re: Yet another UEFI/BIOS question

Le 21-09-2018, à 20:21:06 +0200, Pascal Hambourg a écrit :

Le 21/09/2018 à 08:34, steve a écrit :
Le 20-09-2018, à 20:25:26 +0200, Pascal Hambourg a écrit :

You don't need to convert anything. UEFI can use DOS partition tables.

I know since that's what I'm currently doing.

Doing what ?

Using msdos partition tables.

This is irrelevant because until now you were booting Debian in legacy (BIOS) mode.

Absolutely correct.

I am not talking about you doing anything. I am saying that native UEFI boot (NOT legacy boot) can use a disk with a DOS partition table, provided that it has an EFI system partition (Id 0xef).

Isn't it ef00?

No. ef00 is a gdisk specific mnemonic for the EFI system partition type identifier in a GPT partition table. The actual GUID is C12A7328-F81F-11D2-BA4B-00A0C93EC93B. (0x)ef is the partition type identifier for an EFI system partition in a DOS partition table.

Thank you for the clarification.

Because what I finally did is install a fresh Debian on another device
(using GPT) and the ACPI errors still were there.

In legacy mode (with a BIOS boot partition) or EFI mode (with an EFI system partition) ?

In EFI mode. The "Bios" is now fully in EFI mode and it sees all my boot

I used the opportunity of having another Debian to convert my sda disk
to GPT tables, and change the BIOS setting to UEFI only (just for the
sake of it). So all my disk have a GPT partition table except for the 3
ones for the RAID1 array. Not sure whether I can use the same
manipulations to convert them to GPT also. But since they work fine, I
might leave it as it is.

You can, but IMO it provides little value. GPT is useful in the following cases :
- disk bigger that 2 TiB

Might come sooner or later.

- more that 4 partition without the extended/logical partition kludge
- need to use PARTLABEL or PARTUUD (but RAID uses its own UUID)
- system disk for Windows in EFI mode

I have but it's on it's own disk, so already in GPT.

AFAICS none of these conditions apply to your RAID disks. However I noticed that 2 out of the 3 RAID partition on each disk are logical partitions. This is not necessary if there are only 3 partitions per disk. So in order to get rid of the extended partition kludge, you could either convert the logical partitions into primary partitions or convert the partition table to GPT.

I think I'll do that so to have 100% GPT disks and leave the past where
it is and prepare the future. But this step worries me a bit because I
have all my personal data on one of the RAID1 and really don't want to
loose them. I think best would be to backup those data elsewhere in case
things go wrong.

Thanks a lot for all your very useful insights.

Have a nice week-end


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