Re: I think I've found why Xen domUs can't mount some file-backed disk images! (vnd(4) hides labels!)

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Sun, 11 Apr 2021 15:53:07 +0200
    From:        Manuel Bouyer <bouyer%antioche.eu.org@localhost>
    Message-ID:  <YHL/Q8fU17sVt2e+%antioche.eu.org@localhost>

  | On Sun, Apr 11, 2021 at 01:28:46PM -0000, Michael van Elst wrote:
  | > vnd computes a fake geometry based on 1MB cylinders.
  |
  | Why does this trucates the total number of sectors of the vnd ?
  | there's no reason to do so.

I agree, that's truly stupid.   No-one cares about cyl/head/sect any
more, all disk I/O is done using block numbers ... and even if someone
still had a real hardware interface that used CSH addressing, that's only
an issue for that physical device.   vnd is doing filesystem I/O, that's
all based on byte offsets into the file, which (faked) cylinder would be
used could not possibly be less relevant.   Just fake a chs for the
purposes of the labels, etc, like real modern drives do, after which
everyone ignores that and simply uses block numbers.

kre