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Re: How to prepare an ISO 9660 CD for booting via GRUB ?
From: |
Thomas Schmitt |
Subject: |
Re: How to prepare an ISO 9660 CD for booting via GRUB ? |
Date: |
Tue, 06 Apr 2010 13:26:00 +0200 |
Hi,
i have roughly implemented the missing options
of grub-mkisofs in xorriso and am now comparing
the results.
The ISO image by xorriso boots from CD and from
USB stick. Are there other media types which
would impose a further challenge ?
If so: are there testers who would be willing
to try my ISO image (1.9 MB) on such media ?
------------------------------------------------
It seems that grub-mkisofs does not comply much
to the partition table prescription given by
Vladimir.
The image made by grub-mkisofs has 1550336 bytes
= 757 * 2048 , 3028 * 512.
It bears as partition table:
0000660 0080
0000700 0000 00cd 0000 0001 0000 ffff ffff 0000
0000720 0000 0000 0000 0000 0000 0000 0000 0000
*
0000760 0000 0000 0000 0000 0000 0000 0000 aa55
(od -x regrettably produces big-endian 16 bit.
One has to swap: 00cd is actually cd 00 .)
The xorriso image is currently a bit larger
(see below).
1966080 bytes
= 960 * 2048 , 3840 * 2048
xorriso -toc reports:
ISO session : 1 , 32 , 754s , ISOIMAGE
Partition table:
Image size is 32 + 754 = 786 * 2048 = 3144 * 512
= 0x0C48
I insert 0x00000C47 as end LBA (= 0c47 0000).
End C/H/S is c0,h49,s57 (= 31xx 0039).
0000660 0080
0000700 0002 31cd 0039 0001 0000 0c47 0000 0000
0000720 0000 0000 0000 0000 0000 0000 0000 0000
*
0000760 0000 0000 0000 0000 0000 0000 0000 aa55
Vladimir: does that look ok for you ?
Is 0x0C47 correct to depict image size 0x0C48 ?
Is my C/H/S computation ok ?
(I understand Wikipedia that way, but am not
sure.)
-------------------------------------------------
xorriso produces a larger image because of 64 kB
multi-session preparations, of 300 kB end padding
and of padding to full 32 kB blocks.
Most of this overhead can already be prevented.
I will see whether i can strip the output to
its net size of 754 sectors.
Nevertheless, neither the image of grub-mkisofs
nor of xorriso fit on a vanilla floppy disk.
Is it worth to sacrifice multi-session history
capabilities in order to save 64 kB ?
(If i do not duplicate the ISO superblock then
i cannot mount older sessions of a multi-session
ISO image.)
------------------------------------------------
Compatibility question:
Is the help text of grub-mkisofs
--protective-msdos-label Patch a protective DOS-style label in the image
essential to any frontend of grub-mkisofs ?
I would prefer to print something more neutral.
Like:
--protective-msdos-label Patch System Area by partition table
Any DOS connotation should be obvious by the
option name already.
-------------------------------------------------
Have a nice day :)
Thomas
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, (continued)
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/01
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/01
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/01
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/01
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/02
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/02
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/02
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/02
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/03
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/03
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?,
Thomas Schmitt <=
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/07
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/07
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/09
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/09
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Seth Goldberg, 2010/04/09
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/10
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/10
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/10
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/04/10
- Re: How to prepare an ISO 9660 CD for booting via GRUB ?, Thomas Schmitt, 2010/04/10