Re: [gentoo-user] Re: Is a USB-key-to-hard-drive-tap-dance-boot possible?

["Walter Dnes" <waltdnes@waltdnes.org>]

On Wed, Dec 23, 2020 at 04:16:46AM -0000, Grant Edwards wrote

> Does the UEFI BIOS recognize that /dev/sda1 exists, but just isn't
> bootable? If yes, then it should be possible to install Grub on a USB
> key and boot a kernel on /dev/sda1. It might be simpler to just put
> the kernel and initrd on the USB key also. Though boot time might be
> slightly slower that way, it won't affect performance after that.

  The point of this excercise is to bypass UEFI BIOS as much as
possible.  The machine will happily automatically boot from the Gentoo
minimal install USB key, which I believe is grub, so that works.  And
the minimal install does indeed recognize /dev/sda, which is why I was
able to install linux in the first place.  What I'm looking for is the
grub "recipie" to automatically hand off control to /dev/sda1 at bootup.
This will require leaving a USB key permanently in one of the 6 USB
ports in the back of the machine.

  I've been using lilo for 20 years plus, so I don't have a clue about
grub and how it works.  I generally have 2 kernels available on the lilo
boot menu, "production" and "experimental".  I test the "expermental"
kernel for a while before copying it over the "production" kernel.  My
menu normally waits up to 15 seconds.  If no keypress, it defaults to
the "production" kernel.  Grub would need to load one of
/boot/kernel.experimental or /boot/kernel.production.  I could
re-arrange the layout if necessary.  Here's my current /boot layout...

[d531][waltdnes][~] ll /boot
total 18412
drwxr-xr-x  2 root root    4096 Dec 22 21:42 .
drwxr-xr-x 21 root root    4096 Oct 24 12:14 ..
-rw-r--r--  1 root root       0 Oct 11 19:55 .keep
-rw-r--r--  1 root root       0 Oct 13 05:57 .keep_sys-boot_lilo-0
-rw-------  1 root root  139264 Dec 22 21:42 .map
-rw-r--r--  1 root root 2979997 Dec 21 19:31 System.map.experimental
-rw-r--r--  1 root root 2991033 Oct 13 06:03 System.map.production
-rw-r--r--  1 root root     512 Oct 13 06:04 boot.0800
-rw-r--r--  1 root root   90538 Dec 21 19:31 config.experimental
-rw-r--r--  1 root root   90579 Oct 13 06:03 config.production
-rw-r--r--  1 root root 6214192 Dec 21 19:31 kernel.experimental
-rw-r--r--  1 root root 6271536 Oct 13 06:03 kernel.production

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications