Bug#776317: Jessie RC1 amd64 mini image missing efi bootloader

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

it might be more simple to just append efi.img as
additional partition rather than unpacking it into
the partition for custom firmware.

--------------

The first step with the new argument
 efi_fat="$1"
in util/geniso_hybrid_plus_firmware_partition
and the two alternative calls of
geniso_hybrid_plus_firmware_partition from
build/config/x86.cfg stays as is.

The other two steps get replaced by:

--------------

If "$efi_fat" is not empty, append it to the image
and mark it in MBR.

Depending on the fact that the firmware FAT is aligned
to full MiB and isohybrid padded up the ISO to full MiB,
one could quite duplicate the code of
util/geniso_hybrid_plus_firmware_partition from
line 37 to end:

  # Done!
  echo w
  ) | fdisk -C "$cylinders" -H "$heads" -S "$sectors" "$iso"
+ fdisk_ret="$?"
+ test "$fdisk_ret" = 0 || exit "$fdisk_ret"
+
+ test -z "$efi_fat" && exit 0
+
+ cat "$efi_fat" >> "$iso"
+ 
+ # Until the bug is fixed: Need no new exaggerated cylinder count
+ 
+ (
+ 
+ # Make new partition #3
+ echo n
+ echo p
+ echo 3
+ echo # use default start sector
+ echo # use default end sector
+ 
+ # Set partition type to 0xef : FAT for EFI
+ echo t
+ echo 3
+ echo 239
+ 
+ # Done!
+ echo w
+ ) | fdisk -C "$cylinders" -H "$heads" -S "$sectors" "$iso"

----------

The computation of cylinders seems wrong in
util/geniso_hybrid_plus_firmware_partition:

cylinders="$(($(stat -c %s "$iso") / $heads / $sectors))"

"stat -c %s" yields the byte count of the ISO image.
Cylinder size is $heads * $sectors * 512 bytes.
The 512 is missing in above computation.

Just try:

  $ iso=mini.iso
  $ echo "$(($(stat -c %s "$iso") / 64 / 32))"
  14336

That would be 14+ GiB. More realistic is:

  $ echo "$(($(stat -c %s "$iso") / 64 / 32 / 512))"
  28


--------------------------------------------------------
About letting xorriso set up isohybrid and add partitions
to MBR and GPT:

I am having some conceptional problems in libisofs
to get appended partitions marked in GPT.
The backup GPT of an EFI-enabled isohybrid is supposed
to be inside the block range of the ISO filesystem.
The appended partitions are not. So they should come
after the backup GPT.
But a GPT partition has to be located before the backup GPT.

Can you tell me more about the use cases for the firmware
partition ?
Is it necessary that partition editors can enlarge it ?


Have a nice day :)

Thomas