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

[Andrei Borzenkov <arvidjaar@gmail.com>]

В Tue, 12 May 2015 18:52:22 +0800
Michael Chang <mchang@suse.com> пишет:

> On Fri, May 08, 2015 at 09:53:41PM +0300, 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.
> > 

Actually I think it is useful for all platforms.

> > 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.
> 
> I can only tell it to solve the problem of time wasting in copying
> modules and images creation due to multiple invocation of grub-install
> for doing redundency install. Beside that, do you foresee any other
> improvement it can provide?
> 

You answered it yourself below. That is why I think it is useful mostly
for PC BIOS that is unique with embedding problem.

> > 
> > Patch allows transparently use none or multiple installation devices,
> > similar to
> > 
> > grub_devices="/dev/sda /dev/sda1 /dev/sdb"
> 
> It also looks to me that this patch can solve the problem of multiple
> device install with blocklists. Think about the user installs to mbr
> (sda) and partition (sda1) because he someshow wants the paritition to
> be chainload-able for resuce or for any of his own interests. 
> 
> If the user occasionally do.
> 
> grub-install /dev/sda1 grub-install /dev/sda
> 
> The chainload will fail for sda1 since later install to mbr replaces the
> core.img.
> 

Exactly. This was common problem for openSUSE users as at least in
earlier versions installer defaulted to multiple bootloader locations
and only some of them allowed embedding.

> You patch can avoid such pit-fall by doing it once.
> 
> > grub-install $grub_devices
> 
> What if one of the device failed, should it continue installing the rest
> or abort immediately ?
> 

It will abort, unfortunately. Changing it is really intrusive as it
may happen deep in call chain which simply does grub_util_error(). It
is something that may be considered for the future. BTW as far as I can
tell pbl aborts installation if any of grub-install invocation failed.