Re: How to completely disable all UUID and dynamic probing?

[Pascal-liste]

Le 30/11/2019 à 06:32, Joshua Hudson a écrit :
> How to completely, disable UUID=  and other dynamic probing in grub2?

Can you be more specific ?
GRUB may use UUIDs in different locations.

1) With the root= parameter in the kernel command line. GRUB does not 
use it, it just passes it to the kernel.
You can disable the use of UUIDs there in grub.cfg generated by 
grub-mkconfig/update-grub by setting GRUB_DISABLE_LINUX_UUID=true and 
GRUB_DISABLE_LINUX_PARTUUID=true in /etc/default/grub.

2) In "search" commands used by GRUB to search for a drive or partition, 
e.g. containing a kernel image and initramfs. AFAIK, there is no setting 
to disable it in grub.cfg generated by grub-mkconfig/update-grub, so you 
will have to hack it or disable it and create your own grub.cfg.

3) In GRUB's core image installed by grub-install when /boot/grub is not 
in a plain partition on the same drive as the core image (e.g. on a 
different drive, in a LVM logical volume or a RAID array). Again, AFAIK 
there is no setting to disable it.

> I currently have the bios set to legacy boot, but the bios claims to
> support UEFI. Anyway, the way this works is you get passed a hard disk
> identifier in dl. That's the hard disk to boot. Don't try scanning
> drives, you'll fine multiple copies, most of which are insane.

Do you mean you have duplicate UUIDs ? /This/ is insane.

> You should not
> try to access any other disks at all until the kernel is booted.

The root= parameter in the kernel command line is not used until the 
kernel is booted.

> Everybody's saying don't edit /boot/grub/grub.cfg; edit the config
> files in /etc/grub.

This advice is valid when grub.cfg is automatically generated by 
grub-mkconfig/update-grub after each kernel update, as most 
distributions do, so any manual changes will be overwritten after the 
next update.