bug#26339: [PATCH 02/18] system: Add extlinux support.

[Mathieu Othacehe <m.othacehe@gmail.com>]

> Woow, that was fast!  :-)

I had time to kill during a train trip :)

> Good question!  I guess we need to store the name of the bootloader type
> in the “parameters” file, and then look it up upon switch-generation?
> But maybe we also need to store a reference to the bootloader package so
> that it isn’t GC’d?

We have three options for switch-generation :

1. Do not reinstall bootloader, only update config (current behaviour).

-> It was ok with one bootloader, it's more problematic with multiple
bootloaders. For example switching between two generations with two
different bootloaders.

2. Save the bootloader type in "parameters" and reinstall bootloader
(current bootloader build, not necessarily the one used when creating
this generation)

-> It's the option I choose in my series.

3. Same as 2. but also save bootloader used (store reference) and add a
gc-root to keep it around.

I can try to implement option 3 if you're ok ?

> No better idea, sounds like a good start.
>

Ok.

> I think the most important is to make sure that our current use case,
> where people always use GRUB, doesn’t break.

With my basic-one-unencrypted-partition setup it work fine, but it would
be great if people with more complex setup could try this serie :)

Thanks,

Mathieu