Re: GuixSD bootable ISO-9669 image

[Ludovic Courtès]

Hello!

Chris Marusich <address@hidden> skribis:

> Chris Marusich <address@hidden> writes:
>
>> address@hidden (Ludovic Courtès) writes:
>>
>>>> There appear to be (at least) two problem that prevent this naive
>>>> solution from working, which might point us in the right direction:
>>>>
>>>> First, the GRUB menu is trying to find a file system with label
>>>> "gnu-disk-image" (via "search --label --set gnu-disk-image"), which
>>>> won't work because there is no file system with that label in the
>>>> resulting image.
>>>
>>> So it seems that the crux of the problem is that ISO9660 lacks file
>>> system labels, which breaks the whole thing, right?
>>
>> Yes, probably.  It seems we can set a "volume id", but not a label like
>> in EXT file systems.  For example, see here:
>>
>> https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/installer/cd-dvd/iso-image.nix
>
> I discovered that grub-mkrescue also lets you pass through options to
> xorriso.  So, you can set the volume ID as follows:
>
> $ sudo grub-mkrescue -V gnu-disk-image -v -o /tmp/test-img.iso 
> /mnt/disk-image-partition-1
> ...
> grub-mkrescue: info: enabling BIOS support ....
> grub-mkrescue: info: grub-mkimage --directory 
> '/gnu/store/2hxz9cpipsbf2hkiz5aq70k73wjj0fw1-grub-2.02rc1/lib/grub/i386-pc' 
> --prefix '/boot/grub' --output 
> '/tmp/grub.zilpbK/boot/grub/i386-pc/eltorito.img' --format 'i386-pc-eltorito' 
> --compression 'auto'  --config '/tmp/grub.N4OuA5' 'biosdisk' 'iso9660' 
> ...
> grub-mkrescue: info: executing xorriso -as mkisofs -graft-points 
> --modification-date=2017042404413800 -b boot/grub/i386-pc/eltorito.img 
> -no-emul-boot -boot-load-size 4 -boot-info-table --grub2-boot-info 
> --grub2-mbr 
> /gnu/store/2hxz9cpipsbf2hkiz5aq70k73wjj0fw1-grub-2.02rc1/lib/grub/i386-pc/boot_hybrid.img
>  --protective-msdos-label -o /tmp/test-img.iso -r /tmp/grub.zilpbK 
> --sort-weight 0 / --sort-weight 1 /boot -V gnu-disk-image 
> /mnt/disk-image-partition-1.
> ...
> xorriso : WARNING : -volid text does not comply to ISO 9660 / ECMA 119 rules
> ...
> Writing to 'stdio:/tmp/test-img.iso' completed successfully.
>
>
> Looks like setting the volume ID worked (despite the warning above):
>
> $ sudo blkid /tmp/test-img.iso
> /tmp/test-img.iso: UUID="2017-04-24-04-41-38-00" LABEL="gnu-disk-image" 
> TYPE="iso9660" PTTYPE="dos"

Excellent.  So we would first need to add support for reading ISO9660
labels in (gnu build file-systems), which is what we use instead of
libblkid.  With that in place, we should be almost done.

Ludo’.