>
> This yields an MBR (copied from $old_iso) with partition start
> LBA 64 (16 blocks of 2048)
Hm, that would mean that some crapware like adobe might write between
MBR and first partition.
>
> My test machine boots via BIOS. The ISO image is only equipped
> for BIOS, anyway. I have no means to test UEFI with partition
> offset 16.
>
> Does contemporary grub-mkrescue cause xorriso to produce GPT
> for UEFI ? (That would be a new adventure with -partition_offset.)
>
Yes, and we add HFS+ as well. Isn't this HFS+ catalog sufficient for the
problem at hand?
>
> If anybody has opportunity and curiosity:
>
> It should be possible to append option -partition_offset 16
> to the options of grub-mkrescue, so that it reaches xorriso
> as one of the ${source} arguments.
>
> There was a bug with -partition_offset with older versions
> of xorriso, which caused Debian to stop using this option
> in its amd64 UEFI capable images. So better get newest stable
> xorriso for such a test. Currently this is:
> http://www.gnu.org/software/xorriso/xorriso-1.3.2.tar.gz
>
Can we detect presence of this bug?> > Theoretical problems: > Additional problem you don't mention: consumption of space by additional headers. We use xorriso for making floppies as well (and it works). > El Torito booting from CD/DVD should not be influenced by > this unusual layout. The ISO 9660 image beginning at LBA 0 > is quite the same as without that option. > > Nevertheless, there was a report that Apple "Snow Leopard" > refused to mount an ISO image with partition offset 16. > http://lists.debian.org/debian-cd/2011/04/msg00032.html > http://lists.debian.org/debian-cd/2011/04/msg00040.html > http://lists.debian.org/debian-cd/2011/04/msg00042.html > Note well that this was not about booting. > But it will most likely swallow HFS+-hybrid disk without any problem. Perhaps we should generate HFS+-hybrid even for BIOS-only CDs. Another solution is to have a hybrid ISO + FAT or ISO + HFS+ + FAT layouts. > Further, one never knows what the booting operating system > expects as layout of USB sticks. I consider the current layout > with LBA 1 to be more confusing. But that's only me ... > The reason for the specified partition is twofold: - Some computers check for presence of an active partition. - To avoid some software overwriting the ISO If user desires to have a partition for data he can always add a second partition but it doesn't solve the problem of accessing ISO files. > > Have a nice day :) > > Thomas > > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel >
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