Re: Guidance on conflicts between GNU GRUB and proprietary software

[lsorense@csclub.uwaterloo.ca (Lennart Sorensen)]

On Tue, Sep 28, 2010 at 10:58:31PM +0200, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> On 09/28/2010 10:07 PM, Lennart Sorensen wrote:
> > On Tue, Sep 28, 2010 at 09:43:25PM +0200, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> >   
> >> GPT has new types.
> >>     
> > GPT has an msdos partition type for itself for use in hybrid setups.
> > I know GPT partition tables have new types, but GPT itself has a type
> > reserved in the old dos partition table.
> >   
> You probably mean the 0xee type. But it's used only to mark the whole
> space as used. In our case it's a partition which is identified to have
> all the data deleted. Let's just take a famous collision between Solaris
> and Linux swap. I doubt that any of them willingly choose the type in
> order to collide with other. If Linux relied solely on the partition
> type to identify its swap it would be a disaster for dual-boot system.
 
Certainly true. Now there clearly are unused types.  On the other
hand given the lack of partition entries in the first place, needing a
partition isn't very convinient at all.  It might be a nice option to
support though.  Of course I doubt anything prevents the user of a
partition for grub already, given you could use an MBR that just goes
to the active partition (ie: standard DOS/Windows behaviour), and then
have grub be on that active partition, whatever the type may be.

> Destroying the data which is on its rightful place is bad independently
> what you use the place for, how important your usage is or how
> "unimportant" you judge the current occupant.

Well grub should only install where someone tells it to.

> I believe it's possible to have something something much more reliable.
> We could have a tool grub-mkembed (analog of mkswap) which would mark
> the partition as available for GRUB embedding (perhaps in addition of
> checking type). This signature must be written in a way to be
> overwritten when formatted in known filesystems

Not sure you can pick a place and be certain all filesystems will
overwrite it on format.  You can try, but it won't always work.

> >> GRUB has a design principle of being cross-platform installable.
> >> Moreover the same disk can contain multiple grub installation. I
> >> personally regularly move the disk between yeeloong and amd64 laptop,
> >> well it has only one GRUB since on yeeloong my GRUB is in flash but it
> >> could easily have one on disk too.
> >>     
> > If two architectures expect sector 0 to contain boot code, then that
> > can't work.  I certainly would not consider that a worthy design goal
> > compared to lots of other things.
> >
> >   
> Some architestures are incompatible because of such reasons but many
> others don't conflict in such ways.
> When you abandon a design goal or give an exception you first have to
> make sure that there is no way to reconcile the given features.

Nice to support if possible, although given how short on partitions you
are already with msdos partitions is really seems futile.

> Just one example: I'm ready to give an exception to multiterm design in
> order to get the features required for ubuntu CDs but first I discussed
> in order to find compromise which would result in less mess on codepath
> intersections and it looks like there is actually one.
> In this case taking PReP partition type would be unfounded.

Well I think using a partition at all in the case of the msdos partition
table is a huge inconvinience to people, and I suspect many won't be
able to.

it has become annoyingly common to see:

System restore partition
Windows System partition
Windows partition

That leaves one primary partition on a typical system these days.  So to
make more than one partition, that one has to be extended.  Now where
can grub go?

If the system maker had been nice, they would have used GPT instead and
those 3 partitions would not have been a problem.  But of course windows
doesn't know how to boot from GPT on a normal BIOS based system (unlike
most other OSs that have no such problem).

If people are dual booting, using the track 0 area may be a bad thing.
Unfortunately people that a dual booting are most likely to have partition
limitations making it the only option that works.

-- 
Len Sorensen