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

[Vladimir 'phcoder' Serbinenko]

On Apr 29, 2015 5:35 PM, "Olaf Hering" <address@hidden> wrote:
>
> On Wed, Apr 29, Vladimir 'phcoder' Serbinenko wrote:
>
> >
> > On Apr 29, 2015 5:10 PM, "Olaf Hering" <address@hidden> 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,
This info is already in grub.cfg. Why does grub.cfg need help to find disk with distro if it already contains a refence to it?

>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.
>
And your point is? Just that something is available doesn't mean it's useful
> My laptop with its BIOS provides nothing like that because the concept
> is based on the PC from the 80s. Or whatever.
>
> Olaf
>
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