Re: Multiple partition maps

[Robert Millan <rmh@aybabtu.com>]

On Thu, Sep 04, 2008 at 11:49:21PM +0200, phcoder wrote:
> Robert Millan wrote:
> > On Wed, Sep 03, 2008 at 08:08:50PM +0200, phcoder wrote:
> >> Hello. I was looking at the grub code and seen that if a disk has
> >> multiple partition tables (e.g. macintel with bootcamp) then only first
> >> one will be detected. In some cases it can lead to unreachable
> >> partitions if for some reason partition is present only in one table.
> >> Does anyone has an idea how theese cases may be treated compactly and
> >> efficiently?
> > 
> > Strictly speaking, GPT+MSDOS hybrid tables are a violation of the GPT
> > specification.  It's not clear what would be the "correct" way of handling
> > them.
> > 
> > Since we're not a legacy program, I suppose the sane thing to do would be
> > to abort MSDOS probing if a protective DOS partition (0xee) is found, and
> > then only GPT will be used.
> 
> We're not a legacy application but some OS and partition tools are and
> we have to work with them. I think just some maintenance tools included
> in GRUB should be enough. I'll write them soon. (perhaps even tomorrow)

I don't understand.  Which kind of maintenance do you mean?  GRUB isn't
designed to modify partition maps, only read them.  Perhaps what you want
is more related to Parted?

> > Isn't this what GRUB does already?  I thought it would be...
> > 
> It does. But I don't know if there are other cases similar to this one.

There's also grub-setup.  On an hybrid map the only option is to follow the
GPT install path and search for a BIOS boot partition (or otherwise use
blocklists).  Does it DTRT already?

I don't know of any other similar situation.

-- 
Robert Millan

  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
  how) you may access your data; but nobody's threatening your freedom: we
  still allow you to remove your data and not access it at all."