[gentoo-user] Re: Using UUID for root disk in grub requires initramfs?

[Ian Zimmerman]

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.

With initramfs, this egg/chicken problem is hidden: the initramfs itself
is the initial root fs, and during the pivot to the real root fs
userspace programs [1] are already available.

[1]
Well, usually just 1 of them: busybox.

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