Hi Tomas,
thank you very much for your detailed email. I exceptionally top post as I have
not much to add. Highly appreciated. I will use it as reference for future
changes
in T2.
If you have any suggestion or want to test something out in T2 just always
let us know!
René
On May 2, 2017, at 22:51, Thomas Schmitt <[email protected]> wrote:
>
> Hi,
>
> i wrote:
>>> I [...] wonder what mkisofs option -q might be supposed to do
>
> René Rebe wrote:
>> I did not re-research it right now, but it is possible that a decade ago the
>> option was only -q or something like that, …
>
> I'd say it was never official.
> Antique mkisofs-1.12b3 accepts -q, -qu, qui, -quie, and -quiet like
> genisoimage. But it lists only -quiet in its help text.
> It stems from the time when maintainership changed from Eric Youngdale to
> Joerg Schilling. Obviously Joerg changed this swampy behavior ionly after
> genisoimage was forked from mkisofs in summer 2006. So genisoimage
> inherited it and still shows it.
>
>
>> EFI Grub 2 T2 [...]
>> The ISO glue still needs to be updated for grub2 support.
>
> Let me dump some info for that.
>
> Expect to create a xorrisofs command like this from grub-mkisofs:
>
> xorriso -as mkisofs \
> -graft-points \
> --modification-date=2017042506244800 \
> -b boot/grub/i386-pc/eltorito.img \
> -no-emul-boot -boot-load-size 4 -boot-info-table --grub2-boot-info \
> --grub2-mbr \
> /usr/lib/grub/i386-pc/boot_hybrid.img \
> -hfsplus \
> -apm-block-size 2048 \
> -hfsplus-file-creator-type chrp tbxj \
> /System/Library/CoreServices/.disk_label \
> -hfs-bless-by i /System/Library/CoreServices/boot.efi \
> --efi-boot efi.img \
> -efi-boot-part --efi-boot-image \
> --protective-msdos-label \
> -r \
> --sort-weight 0 / \
> --sort-weight 1 /boot \
> -o output.iso \
> /tmp/grub.MWf3hz \
> ./payload
>
> grub-mkrescue created the local disk tree /tmp/grub.MWf3hz. It contains
> the HFS+ specific file tree ./System, the EFI System Partition image
> ./efi.img, and other GRUB 2 files.
> The xorrisofs options are in part traditional mkisofs and in part they were
> especially created for GRUB 2. One may ask me about the bytes they yield,
> but not so much about their meaning inside GRUB 2.
> https://www.gnu.org/software/xorriso/man_1_xorrisofs.html
>
> Above yields a GPT with no mountable partition that leads to the ISO
> filesystem. Only the EFI partition is mountable. Further there is an
> Apple Partition Map for the HFS+ Macs. The HFS+ filesystem is implemented
> as additional superblock and directory tree which represent the
> directories and files of the ISO.
>
> I have a wrapper script for xorriso, which manipulates the options in a
> way that two mountable MBR partitions emerge. One for the ISO and one
> for the EFI partition.
>
> https://dev.lovelyhq.com/libburnia/libisoburn/blob/master/frontend/grub-mkrescue-sed.sh
> No GPT means no backup GPT, which sits at the end of the device.
> Since the end of the image is hardly end of device, its backup GPT becomes
> immediately dislocated when the image gets onto the USB stick.
> With MBR there is no such problem.
> Together with xorrisofs option -partition_offset 16 one gets a
> conventional partitioning of the USB stick with a gap before partition 1.
> This should please partition editors when the user wants to add more
> partitions.
>
> My MBR based layout does not care for HFS+ (i.e. pre-EFI) Macs. Not even
> the developers of GRUB 2 could tell me which Apple models exactly that
> would be.
> The options for that look be no means less frankensteinish than those
> which grub-mkrescue uses:
>
> xorriso -as mkisofs \
> -graft-points \
> --modification-date=2017042506244800 \
> -b boot/grub/i386-pc/eltorito.img \
> -no-emul-boot -boot-load-size 4 -boot-info-table --grub2-boot-info \
> --grub2-mbr /usr/lib/grub/i386-pc/boot_hybrid.img \
> -eltorito-alt-boot \
> -e --interval:appended_partition_2:all:: \
> -no-emul-boot \
> -iso_mbr_part_type 0x00 \
> -no-pad \
> -append_partition 2 0xef /tmp/grub-mkrescue-sed-efi-img.23861 \
> -r \
> --sort-weight 0 / \
> --sort-weight 1 /boot \
> -o output.iso \
> /tmp/grub.MWf3hz \
> ./payload \
> -partition_offset 16
>
> My wrapper moved ./efi.img out of the tree that gets copied into the ISO.
> efi.img gets appended after the range of the ISO filesystem. Thus it makes
> both ready for being in disjoint partitions. Option -e --interval:... lets
> the El Torito catalog point to it with platform id 0xEF. MBR partition type
> 0xEF marks it as EFI System Partition for the case that it is presented on
> USB stick.
> Option -partition_offset 16 creates a second ISO superblock and directory
> tree which match an MBR partition start of 64 blocks of 512 bytes.
>
> In summary:
>
> $ xorriso -indev output.iso -report_el_torito plain -report_system_area plain
> ...
> El Torito images : N Pltf B Emul Ld_seg Hdpt Ldsiz LBA
> El Torito boot img : 1 BIOS y none 0x0000 0x00 4 2040
> El Torito boot img : 2 UEFI y none 0x0000 0x00 5760 6043
> El Torito img path : 1 /boot/grub/i386-pc/eltorito.img
> El Torito img opts : 1 boot-info-table grub2-boot-info
> ...
> ISO image size/512 : 29932
> ...
> MBR partition table: N Status Type Start Blocks
> MBR partition : 1 0x80 0x00 64 24108
> MBR partition : 2 0x00 0xef 24172 5760
> ...
>
> Note that the ISO superblock at offset 0 claims the whole image as its
> realm. The ISO superblock in partition 1 claims only up to the end of
> partition 1.
> MBR partition type 0x00 is unusual, but there was a report on grub-devel
> mailing list that some EFIs offer the device for booting only if there
> is only one partition of non-zero type.
> Some BIOSes on the other hand want to see the boot flag 0x80 in some
> MBR partition or else they do not execute the x86 code of the MBR.
> (Neither GRUB nor SYSLINUX MBRs interpret the boot flag. But if they
> don't get started by the BIOS they cannot even ignore it.)
>
> SuSE Linux uses a similar MBR based layout for its EFI capable ISOs.
> Difference is that their EFI partition is number 1 and the ISO partition
> is number 2 with a larger offset than mine.
> And of course their BIOS equipment is ISOLINUX rather than GRUB.
>
>
> Have a nice day :)
>
> Thomas
>
>
>
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