Re: [RFC] grub-install: allow none or multiple install devices on PC BIOS

[Andrei Borzenkov]

12.02.2016 21:41, Vladimir 'φ-coder/phcoder' Serbinenko пишет:
> On 08.05.2015 20:53, Andrei Borzenkov wrote:
>> There are two main applications.
>>
>> 1. Omit install device to create generic image intended for chainloading
>> from other master loader. Such image can be put on any device (or file
>> system) and will still be able to find its $root. Currently even with
>> --no-bootsector grub-install optimizes image by skipping UUID search if
>> possible.
>>
>> 2. Redundant installation on multi-device filesystem, RAID or similar.
>> This allows both optimizing image w.r.t. to using --prefix vs. load.cfg
>> as well as creating image just once.
>>
>> Patch allows transparently use none or multiple installation devices,
>> similar to
>>
>> grub_devices="/dev/sda /dev/sda1 /dev/sdb"
>> grub-install $grub_devices
>>
>> where grub_devices can be empty and still do the right thing.
>>
>> This is work in progress, although it is functionally complete and just
>> needs some cleanups.
>>
>> Comments?
> I like the idea and it was on my "nice to have" list for some time. Do
> you want to clean it up first or should I review this version?


I updated it to the current master with small cleanup. See attached.
Open questions

- we probably should not allow empty install list by default. This is
too error prone to have grub-install silently succeed leaving unbootable
system. Should we add special argument or --force will do?

- it still may be useful to be able to force UUID search instead of
encoding partition number irrespectively of install device locations.
But that is separate topic.

- messages from grub-setup need now qualification with device. It is
otherwise confusing when you have several devices and do not know which
one it refers to.

- for completeness this should really be pushed into grub-bios-setup as
well. But this is a lot of work for rather small gain (only when
installing on multiple partitions on the same disk). Most common
applications I had in mind are zero install devices or different disks
in RAID.

- this makes grub-install even less atomic than it is now. It would be
really useful to have framework for alternative /boot/grub locations so
that boot sector always refers to valid boot location. Or notion of
"undo" where we could revert changes.

optional-install-device.patch
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