On Mon, Oct 08, 2012 at 07:53:10PM -0000, Thomas Schmitt wrote: > > However, as the resultant image still appears to not have a valid MBR > > partition table, there doesn't seem to be any advantage to adding this > > option back to our builds for 12.10. So I think we'll leave it as is > > with -partition_offset 16 disabled for now.
> Do you rather mean "no valid GPT" ? That's not what I mean, but it's possible that I'm mistaken. UEFI looks for an EFI system partition, which is supposed to be defined as a GPT partition of type EF00 containing a FAT filesystem. Since this image now boots under UEFI, UEFI is satisfied that it's found a system partition - which I was assuming meant a valid GPT. However, I now see that an MBR partition of type 'EF' will be up-converted to a GPT partition of type 'EF00', which I guess is what is happening here. > The MBR seems to be ok now. After all it made the difference > between boot and not-boot. fdisk remains unhappy with the image, but this may be a separate issue: Warning: /home/vorlon/devel/iso/quantal-desktop-amd64.iso contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table? y Yes n No gdisk in turn reports that the image is MBR-only. > The GPT is there but it usually not recognized because the MBR > is not trivial enough (not a "protective MBR"). This should have > nothing to do with -partition_offset. > If it has, then this would be probably another bug. > I googled a bit and found: > http://www.rodsbooks.com/gdisk/hybrid.html > The described "Hybrid MBR" would differ from mjg's mainly by the > type of the first MBR partition: 0xee rather than 0x00 im mjg's. > So does it help GPT visibility to set byte 450 of the ISO image > to the value 0xee ? (Byte count starting at 0) That doesn't seem to make any difference in whether fdisk/gdisk are happy with it, at least. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1062737 Title: hybrid images do not include a valid GPT To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-cdimage/+bug/1062737/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
