Re: New Downloadable Version

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

Hi,

i wonder whether JD's USB stick is recognized and booted if it has GPT
rather than a MBR/DOS partition table.

So two questions:

----------------------------------------------------------------------
What happens after the USB stick got converted to GPT ?
----------------------------------------------------------------------

Test whether the USB stick yields any other result with GPT than
with the original MBR/DOS partition table.

Let's assume the device file of the USB stick is /dev/sdc.

First change the type of partition 1 from 00 to 83. 00 is a remnant of
earlier layouts where partition 2 was inside partition 1.
But gdisk converts partition 1 only if its type is not 0x00.

  $ /sbin/fdisk /dev/sdc
  ...
  Command (m for help): t
  Partition number (1-3, default 3): 1
  Hex code (type L to list all codes): 83

  Changed type of partition 'Empty' to 'Linux'.

  Command (m for help): w
  The partition table has been altered.
  Syncing disks.
  $

Now let gdisk do the conversion to GPT:

  $ /sbin/gdisk /dev/sdc
  Partition table scan:
    MBR: MBR only
    BSD: not present
    APM: not present
    GPT: not present

  ***************************************************************
  Found invalid GPT and valid MBR; converting MBR to GPT format
  in memory. THIS OPERATION IS POTENTIALLY DESTRUCTIVE! Exit by
  typing 'q' if you don't want to convert your MBR partitions
  to GPT format!
  ***************************************************************

  Command (? for help): w

  Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
  PARTITIONS!!

  Do you want to proceed? (Y/N): y
  OK; writing new GUID partition table (GPT) to /dev/sdc.
  Warning: The kernel is still using the old partition table.
  The new table will be used at the next reboot.
  The operation has completed successfully.
  $

Inspection by gdisk should then yield

  ...
  Partition table scan:
    MBR: protective
    BSD: not present
    APM: not present
    GPT: present
  ...
  Number  Start (sector)    End (sector)  Size       Code  Name
     1              64         9135503   4.4 GiB     8300  Linux filesystem
     2         9135504         9166223   15.0 MiB    EF00  EFI System
     3         9166224         9174415   4.0 MiB     8300  Linux filesystem

It might be that automatic enlargement of partition 3 fails or that it
treats badly the GPT backup at the end of the USB stick.
But this potential flaw will only occur after booting has succeeded.

----------------------------------------------------------------------
Does the USB stick boot with a Debian netinst ISO ?
----------------------------------------------------------------------

Put this rather small ISO onto the USB stick and try whether it boots
to an installation menu that says "Debian":
  https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.0.0-amd64-netinst.iso

This ISO uses ISOLINUX for BIOS and GRUB for EFI. It has the older
partition table layout that needs partition 1 to have type 00.

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

Have a nice day :)

Thomas