Re: Booting an old PC to SSD that the BIOS cannot see

[Robert Furber]

On 2020-12-30 1:39 a.m., Pascal Hambourg wrote:
> Le 30/12/2020 à 08:08, Glenn Washburn a écrit :
> > On Tue, 29 Dec 2020 15:33:50 -0800
> > Robert Furber via Support requests for the GRand Unified Bootloader
> > <help-grub@gnu.org> wrote:
> (...)
>
> The heavy job is done after the kernel and initramfs have been loaded 
> by GRUB, and does not use /boot.
Obviously I need to learn more about initialization. I was under the 
mistaken impression that all the initialization was done by Grub. Can 
anyone point me towards step by step documentation that explains how a 
Linux PC is initialized? What role ramfs plays? What programs initialize 
the various h/w devices, file systems, etc.? Is it done by the Linux 
kernel?

Presumably, it is the post Grub initialization s/w that takes that takes 
time. And, it has to be accessed from the boot drive recognized by BIOS. 
If this is the case, it may be theoretically possible to split the 
initialization with step1 on the boot drive that initializes the NVMe 
SSD and step2 on the NVMe that initializes everything else.

The expedient solution appears to be to use a small, cheap SATA SSD as 
the boot drive and the NVMe SSD as the working drive, for everything 
else, a la Chris Green.