[bug #46716] Protective MBR partition is not marked as bootable

[Alexander E. Patrakov]

URL:
  <http://savannah.gnu.org/bugs/?46716>

                 Summary: Protective MBR partition is not marked as bootable
                 Project: GNU GRUB
            Submitted by: patrakov
            Submitted on: Сбт 19 Дек 2015 11:37:38
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Alexander E. Patrakov
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 
                 Release: 2.02~beta1
         Reproducibility: Every Time
         Planned Release: None

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Details:

Some old BIOSes (including the one in Intel DG965SS desktop board) refuse to
treat a USB drive as bootable if it has no bootable MBR partitions. This
applies to all iso images that are created by grub-mkrescue and written to a
USB flash drive with dd.

Changing the byte at offset 0x1be to 0x80 in the resulting iso makes it
bootable on such boards.

Images produced by xorriso with isolinux as recommended at
http://www.syslinux.org/wiki/index.php/Isohybrid do have 0x80 at offset 0x1be,
so I think it is a bug in GRUB, not in xorriso.




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