Comment 36 for bug 1899308

Hi,

i confirm that

  groovy-desktop-amd64.iso1 1 5740827 5740827 2.8G ee GPT
  groovy-desktop-amd64.iso2 * 0 0 1 512B 0 Empty

is the indication that the --mbr-force-bootable hack is applied.
A nearly non-existend MBR partition not overlapping the partition of
type EE and carrying the boot flag. It is not really compliant to the
idea of a Protective MBR in UEFI specs about GPT. But the same specs say
(quoted from UEFI 2.8):
  "A Partition Record that contains an OSType value of zero or
   a SizeInLBA value of zero may be ignored."

As for more tweaks: Since i began to participate in bug 1886148 we tried
everything that makes sense with GRUB for PC-BIOS.
We began with a lame mock-up of the old barely legal layout that was used
with ISOLINUX isohybrid. Then we moved to a neat MBR partition table only
to learn that the Lenovos don't like it. Then we moved to GPT and learned
that several old HPs don't like it. Then we used the hack that was invented
five years ago for https://savannah.gnu.org/bugs/?46716 . This helped with
about half of the HPs ... sometimes.

Now we are out of alternatives, unless we revive ISOLINUX for BIOS and
the multi-hack layout of the released Ubuntu ISOs.

Have a nice day :)

Thomas