Bug#502446: debian-installer: grub-installer is not updated for grub-pc introduction
On Mon, Nov 17, 2008 at 12:09:56AM +0900, Osamu Aoki wrote:
> On Sun, Nov 16, 2008 at 12:40:12PM +0100, Robert Millan wrote:
> > On Sun, Nov 16, 2008 at 07:36:52PM +0900, Osamu Aoki wrote:
> > >
> > > I wonder why we offer to install grub-pc to non-MBR locations in lenny.
> > > For me, disabling that is an option. But fixing it is even nicer.
> >
> > Erm, we shouldn't be doing this. When installing in a partition head, you
> > can't really check if there will be enough space. It depends on how much is
> > reserved by your filesystem of choice, which is often not enough anyway.
> >
> > And even if it is, it's an ugly hack to reuse a partition for two different
> > things at the same time.
>
> Hmmm... interesting thought. If this is true, I agree we should drop
> asking non MBR location.
>
> But many Linux distros allow us to install boot loader in chain-loading
> mode at MBR or head of partition of ext2/3 as I remember.
>
> I thought for modern HDD with LBA, there is always first track = 63
> sectors = 31.5KiB available in MBR and partition head (formatted with
> ext2/ext3/vfat/... at least) which grub assumes to use for GRUB Stage
> 1.5. (I know there were days when I envyed HDD with 10 MB capacity and
> only 17 sector per track. Then grub should have problem istalling it
> to it.)
The ~32 kiB after MBR can be assumed to be present, since all but very rare
partitioning software will leave that gap. This doesn't depend on the
filesystem, as it's a partitioning issue.
What each filesystem reserves in its partition head, depends entirely on the
filesystem implementation. GRUB doesn't use heuristics to determine if it'll
fit, and it doesn't make any promise about that.
--
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."
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