Thomas Schmitt wrote: > 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 ? > > Floppy. (supported for image sizes smaller than 1.44 MiB) > 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. > > Yes, grub-mkisofs code is a stub. What I described is a correct table > 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 ? > Yes > Is my C/H/S computation ok ? > It looks fine > ------------------------------------------------- > > 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. > We probably need a way to choose a subset of modules for floppies > > 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.) > > Perhaps as an option, not as default. > ------------------------------------------------ > > 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. > > msdos is the name of this partition label > ------------------------------------------------- > > > Have a nice day :) > > Thomas > > > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > http://lists.gnu.org/mailman/listinfo/grub-devel > >
-- Regards Vladimir 'φ-coder/phcoder' Serbinenko
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