running grub-install / grub-mkconfig from livecd/dvd/usb

[Kenneth Andresen]

I have finally installed grub2 on a SD memory stick from a persistent
LiveUSB, however I ran into several difficulties during the install; the
main ones where as follows:

1) Running grub-install and grub-mkconfig from within a persistent
liveUSB session cause grub not to find the root device. The "mount"
command returns "rootfs on / type rootfs (rw)".
For grub-install the work-around is to use the "--root-device" parameter
and point it to where the installation is desired, for grub-mkconfig I
found no immediate workaround but selected to create my own grub.cfg by
hand. It may be smart to add the --root-device parameter to all the
commands such as grub-mkconfig that requires figuring the root-device.

2) As from the above, the parameter "--root-device" may cause problems
later on(?) In my case I used some time to figure out that --root-device
in fact was not the device that was root on the system I was currently
running, but the root device I wanted to install to. I am imagining
several alternative problems later on where we are using separate root
and boot partitions which may be on entirely different devices from each
other. Due to the lack of GPT support under Grub legacy, I am frequently
having a boot partition on a disk with msdos label but with everything
else on the GPT device.

3) The "device.map" file creates links between (hd0) /dev/sda, (hd1)
/dev/sdb, (hd2) /dev/sdg and so on. Notice /dev/sdg - this is due to my
system having a built-in card reader, and firewire/usb disks are
detected after these card reader entries even though they contain no
memory sticks. I am experiencing instability in the use of /dev/sda and
so on - frequently I find my firewire external disk detected as /dev/sda
instead of my internal one. Would it be possible to use something more
specific as device.map entries?; such as:
(hd0) UUID=xxx-xxxx-xxxxx or (hd1) label=...

I would like to use UUID and or label also inside the grub.cfg instead of
root (hd0)
such as
root (UUID=xxx-xxxx-xxxxx)

4) When booting into my new shiny SD memory bootable stick and pressing
ctrl-c and typing help, I am presented with a long list of options - I
suspect a larger part of the help has scrolled beyond my screen. I tried
with "help | more", but that did not result in anything. Is there an
easy way to while in grub get the full help listing in a similar way to
the intended use of "help | less" pr "help | more"?

These where my initial findings from my first setup of grub2 so if there
are any tricks I may use such as force the order of /dev/sda ...
/dev/sdh to always be the same or something, I would greatly appreciate it!


-- 
Best regards,
Kenneth

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