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 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
