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SubjectRe: linux-2.4.0 breaks grub install into partition
Andries Brouwer wrote:
> On Mon, Jul 10, 2000 at 03:31:12PM -0700, H. Peter Anvin wrote:
> > I see. Yes, Genesis writes to /dev/hda1, and if GRUB is writing to
> > /dev/hda then I would agree 100% that GRUB is buggy.
> What a strange idea. The kernel is broken.
> > you're playing on the kernel's turf by messing with a mounted filesystem
> There are also alias problems without mounted filesystems.
> It is just that the kernel fails to translate blocks on hda1 into
> blocks on hda or vice versa. At first sight this seems quite doable.
> (Given block N on hda, walk the partition list to find the partition
> it is in. When not found the block is hda's responsibility, otherwise
> it now becomes block N-N0 of hda3.)

Doesn't that seem awfully expensive to you? The reverse translation
would be cheaper (instead of thinking of a block as block N on hda3
think of it as N+N0 on hda, at all times throughout the kernel), but it
would still impose an overhead -- perhaps small enough not to matter.

I noticed that the BLKPG ioctl is documented as having a
read_all_partitions() call, which isn't implemented; nor does
/proc/partitions contain the base offset of each partition -- which I
must say makes me wonder what use /proc/partitions was intended to serve
at all. Nor does it seem that these exists an ioctl() to find the base
device and offset for a partition subdevice, which I have to admit to
being rather shocked to find out.

I don't have these issues in Genesis, since I simply specify the
location to install the boot loader by path (e.g. genesis /boot). I
have to admit to being at a loss why GRUB would need to mess with the
boot sector of an arbitrary partition that could not be specified
differently. Note that this is quite different from saying it should
not be able to *ACCESS* such partitions, but that's a completely
different ball of wax.


<> at work, <> in private!
"Unix gives you enough rope to shoot yourself in the foot."

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