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

[Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>]

At 19:20 +0000 on 09 Nov (1163100017), John Levon wrote:
> pygrub-automatic
> 
>       - Default to using pygrub if there's no kernel and no bootloader
>         specified.

Sure, that seems like a good idea.  This should be documented in 
tools/examples/xmexample* too.
 
> pygrub-default
> 
>       - 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?

> 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.

> pygrub-solaris
> 
>       - 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.

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)

Cheers,

Tim.

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