[bug#27529] [PATCH] bootloader: Use <menu-entry> for the bootloader side.

[Ludovic Courtès]

Hi Danny,

[+Cc Mathieu.]

Danny Milosavljevic <address@hidden> skribis:

> On Sun, 02 Jul 2017 16:59:55 +0200
> address@hidden (Ludovic Courtès) wrote:
>
>> Danny Milosavljevic <address@hidden> skribis:
>> 
>> > * gnu/bootloader.scm (menu-entry-device-mount-point): New variable.  
>> > Export it.
>> > (<menu-entry>: New field "device".
>> > * gnu/bootloader/grub.scm (grub-confgiuration-file): Handle <menu-entry>
>> > entries.
>> > * gnu/bootloader/extlinux.scm (extlinux-configuration-file): Handle
>> > <menu-entry> entries.
>> > * gnu/system.scm (menu->entry->boot-parameters): Delete variable.
>> > (boot-parameters->menu-entry): New variable.  Export it.
>> > (operating-system-bootcfg): Make OLD-ENTRIES a list of <menu-entry>.
>> > * guix/script/system.scm (reinstall-bootloader):  Fix bootcfg usage.
>> > ---
>> >  gnu/bootloader.scm          |  3 +++
>> >  gnu/bootloader/extlinux.scm | 19 +++++++++----------
>> >  gnu/bootloader/grub.scm     | 27 ++++++++++++---------------
>> >  gnu/system.scm              | 29 ++++++++++++++---------------
>> >  guix/scripts/system.scm     | 10 +++++-----
>> >  5 files changed, 43 insertions(+), 45 deletions(-)  
>> 
>> Could you explain the rationale?
>> 
>> IIRC there was the idea that implementations of the bootloader API
>> should use <boot-parameters>, and that <menu-entry> would be used only
>> in the user-facing APIs (it had even disappeared with the initial
>> thing.)
>
> Yeah, it's preparation for chainloading support (non-Linux OSes etc).  I 
> don't feel strongly one way or another but I think those chainloading entries 
> would actually be menu entries and not really boot-parameters as in 
> Guix-can-use-them-for-anything.
>
> What this does is use boot-parameters for stuff which Guix needs for itself, 
> and menu entries (which could be a poem by Goethe as much as Guix cares) for 
> the rest.  *Some* boot-parameters will end up as menu entries, but not all 
> (for example think of chainloading: There would only be a menu-entry for 
> chainloading, but both a boot-parameter and a (generated) menu-entry for the 
> Guix Linux kernel).

OK, makes sense to me.  So users can provide menu entries for, say,
GNU/Hurd or GNU/kFreeBSD; Guix would not try to interpret them and
instead pass them directly to GRUB & co., right?

> There would be no way to get from a <menu-entry> to a <boot-parameter> 
> because it could as well make no sense to do that.
>
> In short, the bootloader would always and only get menu-entries, but the 
> remainder of Guix would only use them as support under wobbly chairs or 
> something :)

OK.

> On the other hand, boot-parameters are things which Guix needs and manages.
>
> If we want that (or want it again - it was that way before), this patch would 
> be a way to do it.  If not, I'm fine with it as well.  It just bothered me a 
> bit even when the (otherwise great) multi bootloader support went in that it 
> used boot-parameters as some kind of menu-entry substitute.  In the 
> beginning, <menu-entry> was grub-private, so that was the only way to get the 
> multi bootloader support to work.  But now the <menu-entry> is public.  Then 
> why not use it for what it is?

That makes sense to me.

Mathieu, WDYT?

Thanks for explaining,
Ludo’.