GRUB_DISABLE_INITRD should imply GRUB_FORCE_PARTUUID

[Steve Langasek]

Currently, if you want to boot a Linux system without an initrd, you have to both set GRUB_DISABLE_INITRD=true, and set GRUB_FORCE_PARTUUID to the value of the partition uuid of the root filesystem.

disabling initrd boot only works if your root filesystem is specified in a syntax
If GRUB knows the root device, it should be able to probe the partition uuid of it without having to ask.

If the root disk is specified in a format that is known to not be resolvable by the kernel (LABEL= or UUID=), and grub is not able to resolve this to a partition uuid at update-grub time, then GRUB_DISABLE_INITRD=true should be a no-op. We should not construct a grub.cfg that we know will not boot.

However if grub is able to resolve it, then GRUB_DISABLE_INITRD=true should automatically probe the PARTUUID and use it rather than requiring it to be hard-coded.

[Mathieu Trudel-Lapierre (cyphermox)]

Moving to ubuntu-17.05 so it remains on my todo list, I'll get to it immediately after the zesty release.

[Paul Menzel (paulmenzel)]

I tried to upstream the non-initrd patches in 2019 [1], but got some feedback.

@vorlon also makes a valid point here, so I wanted to ask, if there has been done any work on this.

[1]: https://lists.gnu.org/archive/html/grub-devel/2019-02/msg00055.html