Re: passing options to grub in xen,openfirmware and efi

[Olaf Hering <olaf@aepfle.de>]

On Wed, Apr 29, Vladimir 'phcoder' Serbinenko wrote:

> 
> On Apr 29, 2015 5:10 PM, "Olaf Hering" <olaf@aepfle.de> wrote:
> >
> > On Wed, Apr 29, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> >
> > > I'm aware of the problem and I fully agree with you. Automatic install
> > > doesn't use those and I think the reason for it was to specify root in
> > > early days of porting. I don't think it's used for anything nowadays.
> >
> > For PV guests the use case is simple: provide a generic grub binary,
> > which recognizes optional knobs from the domU.cfg. This will be used to
> > select one of the configured devices as root.
> More details on this one please. Both command line and grub binary are on host.
> How is managing changing one is different from the other?

Not sure what you are asking, but:
The distro provides a static binary, which has a certain level of
features. And some of the features can be controlled from the outside by
some knobs. The feature is to select a certain drive without user
interaction, and the knob is a string in the cmdline in the PV domU
case.

> > > Also unless there is a good usecase for having command line parsing, I'm
> > > all for killing existing ieee1275 parsing altogether and not introducing
> > > any parsing in the future.
> > So you want to dumb it down to the 80s PC level, even if some firmware
> > implementations can set knobs?!
> "It's shiny and new" or "this is from 80s" are fallacies and not arguments.

Its not new that a firmware provides an interface to query its
properties AND that a firmware provides an interface the adjust
properties. OF does that. EFI maybe, no idea. And in some sense a PV
guest via its cmdline does that as well. I have however not looked how
the cmdline is passed to the PV kernel and how its retrieved in the PV
kernel.

My laptop with its BIOS provides nothing like that because the concept
is based on the PC from the 80s. Or whatever.

Olaf