Re: Bootloader udeb selection for specific platform
-------- Original-Nachricht --------
> Datum: Fri, 04 May 2012 21:18:16 -0500
> Von: "Félix Arreola Rodríguez" <firstname.lastname@example.org>
> An: Gerhard Pircher <email@example.com>
> CC: Joey Hess <firstname.lastname@example.org>, email@example.com
> Betreff: Re: Bootloader udeb selection for specific platform
> El vie, 04-05-2012 a las 14:07 +0200, Gerhard Pircher escribió:
> > -------- Original-Nachricht --------
> > > Datum: Thu, 3 May 2012 20:36:21 -0500
> > > Von: "Félix Arreola Rodríguez" <firstname.lastname@example.org>
> > > An: Gerhard Pircher <email@example.com>
> > > CC: firstname.lastname@example.org
> > > Betreff: Re: Bootloader udeb selection for specific platform
> > > Another suggest is that, the boot loaders udebs, provide the virtual
> > > udeb package "bootable-system"
> > >
> > > Your udeb must install the boot loader, and when the udeb is done,
> > > the main-menu will choose finish-install automatically.
> > Okay, but I guess this will not be sufficient to tell d-i that it
> > should use _exactly_ my bootloader udeb package during the
> > installation, as almost every bootloader in d-i defines "bootable-
> > system" in its control file. Would the "Architecture" and especially
> > the "XB-Subarchitecture" field help here?
> > Ah, I see. Though there are bootloaders udebs that don't check for any
> > platform i.e. subarchitecture in its isinstallable file (for example
> > yaboot). And then there's grub, which also works on powerpc/chrp
> > machines. This way d-i could still choose between two bootloaders
> > for this platform. I suppose there must be an additional priority
> > scheme, which tells d-i to use a specific bootloader udeb. Does this
> > have something to do with the "XB-Installer-Menu-Item:" field in the
> > control field?
> Well, yes. You can use a slightly small number in Menu-Item to make it
Okay, so which bootloader gets installed is determined by:
1. the architecture and subarchitecture fields in the udeb's control file
2. the Menu Item Number (defines the order in which bootloader packages
3. the isinstallable script (if that returns 1, then it goes on to the
next bootloader package with a higher menu item number)
> You can check Debian Installer Internals  & the Menu Item Numbers 
>  http://d-i.alioth.debian.org/doc/internals/
>  http://d-i.alioth.debian.org/doc/internals/apa.html
Thanks! I read over the docs before, but didn't get a clear picture how
all these things work together.
The only thing that still confuses me is the subarchitecture field.
 indicates that the yaboot bootloader works for all CHRP platforms:
7300 palo-installer (hppa)
yaboot-installer (powerpc/powermac_newworld, powerpc/chrp*)
(note the asterisk after powerpc/chrp)
However the subarchitecture field in yaboot's control file defines
"... chrp, chrp_r6k, chrp_ibm...". Does this also match on chrp_pegasos
(as probed for in GRUBs isinstallable file)? I guess not, because
"chrp_r6k" and "chrp_ibm" are also defined. But I'm not 100% sure...
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