[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: custom Debian installation ISO image


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 ?)

Some questions:

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

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

> 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 

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 ?

> 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.

Have a nice day :)


Reply to: