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Re: custom Debian installation ISO image

On Sun, 30 Jun 2013 13:54:36 +0300, Thomas Schmitt <scdbackup@gmx.net> wrote:

Thank you for such a prompt reply!

Eugene Paskevich wrote:
dmesg shows the following error:
attempt to access beyond end of device
sr0: rw=0, want=XXX, limit=YYY
where YYY is constant and less than XXX.

If i understand you correctly then the ISO image shows no such
problems when mounted by an already running Linux system.
You experience this only while booting (by a VM, so far).


If so, then i would expect that the booting firmware applies
some offset to addresses. Maybe it is confused by the isohybrid
MBR with non-zero partition start.

(What version of xorriso are you using, btw ?)

Pardon, it's Debian sid's 1.2.2-2.

Some questions:

How much is XXX larger than YYY ?
Please show some example numbers.

For example, now want=1063744, limit=1024000

If you divide the byte size of your ISO file by YYY,
do you get 512 or 2048 ?

Erm... 548405248 / 1024000 = 535.552

Even more, the test for md5sums showed that a whole lot of 15 files
(in my particular case) were inaccessible due to that error.

That should be those with the highest block addresses.

If you do

  xorriso -indev ...your.iso.file... \
          -find / -sort_lba -exec report_lba \
  | tail -15

I've rebuilt the image since then, now it's 50 files.
And yes, those 50 files are exactly the last ones being sorted on LBA address.

Do you get listed the problem files like

  File data lba:  0 ,  2011513 ,        4 ,     7240 , '/root/.viminfo'

If you multiply the numbers in the second number row (here 2011513)
by 2048, do the results exceed the byte size of the ISO image file ?

The earliest "missing" file starts on 254390.
254390 * 2048 = 520990720 (less than ISO size)
The last file starts on 267309.
267309 * 2048 = 547448832 (still less than ISO)

it's hybrid. But let's not think of USB at the moment because
I'm testing the image with VirtualBox.

Try whether omitting
  -partition_offset 16
  -isohybrid-mbr /usr/lib/syslinux/isohdpfx.bin
does help.
These are hacks which have their benefits and often happen to work.
Nevertheless they are not foreseen by firmware that boots (pseudo) CD.

But omitting isohybrid will make this image unbootable from USB?
And omitting partiotion_offset doesn't help.

Eugene Paskevich             |   *==)-----------   |     Plug me into
eugene@raptor.kiev.ua        |   -----------(==*   |      The Matrix

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