Re: [Xen-devel] [RFC] bootloader improvements

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

On Fri, Nov 10, 2006 at 11:05:27AM +0000, Tim Deegan wrote:

> >     - Make pygrub be the "default" bootloader and understand that
> >       keyword.
> 
> I don't understand why this is needed.  Why not just not set a
> bootloader= option if you want the default?

I don't understand your point. The name and location of 'pygrub' should
be an internal detail unless somebody /wants/ to use a different
bootloader. It's a natural follow-on for the first patch.

> > pygrub-kernel-config
> > pygrub-no-grub
> > 
> >     - The combination of these patches allows pygrub FS code to be
> >       used in a hands-off manner. Note that this can also be used to
> >       fix the problem pygrub currently has with restart, by
> >       specifying the kernel/ramdisk explicitly in the config. The
> >       split between "boot kernel" and "configured kernel" might need
> >       some xen api/lifecycle changes too?
> 
> Hmmm.  I like the idea of splitting the bootloader's suggested
> kernel/etc from the config file's one, but I don't think the bootloader
> should be involved in that at all.  I'd rather have Xend be able to make
> a decision based on all the information from both sources.   This needs
> a bit more thought generally.

Could you expand a bit more on what you mean here?

> >     - Solaris domU's will typically never change the kernel/ramdisk
> >       path they use, except if someone's debugging etc. Add some
> >       logic to pygrub so it knows what to do.
> 
> Autodetecting Solaris seems fine, but from that patch it looks like
> pygrub will always choose Solaris even if there's a grub menu.lst in the
> guest.  I'd prefer that to be the other way around: always use the menu
> file, even if we think we can see Solaris.

There /is/ no menu file on Solaris domU.

> Could this code, instead of just overriding the menu code entirely, just
> add another line to the grub menu that contains the default Solaris
> config?  That way if there's no menu.lst, you get a single-item menu for
> Solaris, and even if there is a menu.lst, you still get the choice of a
> "vanilla" Solaris boot.  Something like:
> 
>   sol_lines = ["title Default Solaris boot",
>                "kernel %s %s" % (sol_krnl, sol_args),
>              "ramdisk /platform/i86pc/boot_archive" ]
>   sol_img = grub.GrubConf.GrubImage(sol_lines)
>   g.cf.images.append(sol_img)

Why? I don't understand why replacing a hands-off method with a load of
interactive gook is a step forward.

regards,
john

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