On Sat, Jul 20, 2019 at 2:37 AM Ian Zimmerman <itz@very.loosely.org> wrote:

On 2019-07-19 20:58, Adam Carter wrote:

> I experimented found the following worked in /etc/default/grub;
>
> GRUB_DEVICE="PARTUUID=d3554d49-02"
>
> Which writes grub.cfg as;
> linux /vmlinuz-5.2.0-gentoo root=PARTUUID=d3554d49-02 ro
> init=/usr/lib/systemd/systemd iommu=pt raid=noautodetect
>
> PARTUUID looked up with blkid. No initramfs required :)

I don't get this. blkid is userspace. The _kernel_ needs to know what
the root fs device is, before it even starts pid 1.

Sorry I was misleading by not using chronological order. The steps are;

1. Use blkid to look up the PARTUUID of the root partition

2. Add this to /etc/default/grub as GRUB_DEVICE="PARTUUID=d3554d49-02"

3. run grub-mkconfig

4. Reboot