--- Begin Message ---
- To: submit@bugs.debian.org
- Subject: live-wrapper: debian-live-9.4.0-amd64-xfce.iso image file is larger than its isosize
- From: "Thomas Schmitt" <scdbackup@gmx.net>
- Date: Fri, 18 May 2018 12:18:23 +0200
- Message-id: <2303177774933145517@scdbackup.webframe.org>
Source: live-wrapper
Version: which made debian-live-9.4.0-amd64-xfce.iso, possibly newer than 0.7
Severity: normal
Dear Maintainer,
as Mike Kupfer pointed out in
https://lists.debian.org/debian-user/2018/05/msg00522.html
the file size of
debian-live-9.4.0-amd64-xfce.iso
is larger than the filesystem size reported by
isosize -x debian-live-9.4.0-amd64-xfce.iso
It is undesirable to have sizes differing between filesystem and image file,
because
https://www.debian.org/CD/faq/#verify
proposes to use isosize for determining the checksummed size on a medium
which does not mark the end of the image file copy.
The difference is 32 KiB. It pads up the image file to full multiples of
64 KiB.
The reason for this padding is the multi-session preparation of xorriso
which is done by default if the native command set is used. It is disabled
by default in mkisofs emultation.
debian-live-9.3.0-amd64-xfce.iso was not affected because its filesystem
size was already aligned to 64 KiB.
---------------------------------------------------------------------------
Proposal:
Add to the xorriso run of live-wrapper the command
-compliance no_emul_toc
which will disable the multi-session preparation.
---------------------------------------------------------------------------
Test made:
I repacked debian-live-9.4.0-amd64-xfce.iso by mounting it as /mnt/iso
and running xorriso similar to the recorded run in its file
/.disk/mkisofs
with the proposed command added.
xorriso-1.4.6 \
-outdev /dvdbuffer/x.iso \
-volid 'd-live 9.4.0 xf amd64' \
-padding 0 \
-map /mnt/iso / \
-chmod 0755 / -- \
-boot_image isolinux dir=/isolinux \
-boot_image isolinux system_area=/dvdbuffer/isohdpfx.bin \
-boot_image any next \
-boot_image any efi_path=boot/grub/efi.img \
-boot_image isolinux partition_entry=gpt_basdat \
\
-compliance no_emul_toc
The resulting file /dvdbuffer/x.iso has 1951432704 bytes.
isosize -x reports the matching number of 952848 blocks of 2048 bytes.
There remains the riddle why i cannot find xorriso command
-padding 0
in
https://sources.debian.org/src/live-wrapper/0.7/lwr/xorriso.py/
/.disk/mkisofs indicates that it has been added to the argument list between
self.args.extend(['-volid', self.volume_id])
and
self.args.extend(['-map', cdroot, '/'])
But the code does not do this.
---------------------------------------------------------------------------
Background:
Multi-session preparation on overwritable media (e.g. data files or DVD+RW)
writes the first session to block 32 ff. and writes a superblock copy to
block 0 ff. The session gets aligned to full 64 KiB to avoid remaining
garbage between this session and the next to come, which will start at the
aligned end address.
Each new session overwrites the superblock copy at block 0 ff. This way a
chain of recognizable sessions and their superblocks is created.
xorriso command -toc can then tell where each session begins and thus how
it can be mounted by mount(8) option -o sbsector=.
As example see one of my daily backup DVD+RWs with base session at block 32
and add-on sessions at 32-block-aligned start blocks ("sbsector"):
Media blocks : 1996256 readable , 298848 writable , 2295104 overall
TOC layout : Idx , sbsector , Size , Volume Id
ISO session : 1 , 32 , 1242005s , HOME_Z_2018_04_24_220414
ISO session : 2 , 1242048 , 39682s , HOME_Z_2018_04_25_221507
...
ISO session : 20 , 1908992 , 44177s , HOME_Z_2018_05_16_223024
ISO session : 21 , 1953184 , 43051s , HOME_Z_2018_05_17_223716
Media summary: 21 sessions, 1995881 data blocks, 3898m data, 584m free
Media nwa : 1996256s
---------------------------------------------------------------------------
-- System Information:
Unknown. The problem occurs during Debian Live CD production.
Have a nice day :)
Thomas
--- End Message ---
--- Begin Message ---
Source: live-wrapper
Source-Version: 0.8
We believe that the bug you reported is fixed in the latest version of
live-wrapper, which is due to be installed in the Debian FTP archive.
A summary of the changes between this version and the previous one is
attached.
Thank you for reporting the bug, which will now be closed. If you
have further comments please address them to 898995@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.
Debian distribution maintenance software
pp.
Jonathan Carter <jcc@debian.org> (supplier of updated live-wrapper package)
(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Format: 1.8
Date: Wed, 13 Feb 2019 15:56:34 +0000
Source: live-wrapper
Binary: live-wrapper live-wrapper-doc
Architecture: source all
Version: 0.8
Distribution: unstable
Urgency: medium
Maintainer: Debian Live <debian-live@lists.debian.org>
Changed-By: Jonathan Carter <jcc@debian.org>
Description:
live-wrapper - Wrapper for vmdebootstrap for creating live images
live-wrapper-doc - Wrapper for vmdebootstrap for creating live images (Documentation
Closes: 898995
Changes:
live-wrapper (0.8) unstable; urgency=medium
.
[ Steve McIntyre ]
* Add "-padding 0" to the xorriso command line to remove padding in the
ISO image, as suggested by Thomas Schmitt.
* Add -compliance no_emul_toc to the xorriso command line, as suggested
by Thomas. Closes: #898995
.
[ Jonathan Carter ]
* Add "quiet splash" to cmdline
* Update standards version to 4.3.0
* Update to debhelper-compat (=12)
* Add self to uploaders
* Replace python-sphinx with python3-sphinx
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1fc3795502ca625a966b5345612f9cbc4c533112 29296 live-wrapper-doc_0.8_all.deb
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Files:
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3c2506c0555333a32b5505c3c2b22b6d 8918 misc optional live-wrapper_0.8_amd64.buildinfo
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