DOS ain't dead

failed with hybrid MBR under Windows (Users)

posted by RayeR , CZ, 11.05.2026, 07:47
(edited by RayeR on 11.05.2026, 13:40)

Oh sh... even worse with Win7 and hybrid MBR. I found that Windows is actively corrupting the GPT at LBA 2 (offset 400h) whenever I run command "attributes volume clear hidden" in diskpart - this is necessary to unhide my legacy MBR partitions because Windows hides automatically them at boot when detect hybrid MBR with EEh entry. So definitely not possible both legacy and GPT partition together. I hate this windows behavior to silently write something somewhere in a God/good intention. All that crap started by Win95 unexpectedly writting to floppies...

So I wiped the GPT and roll back to old good MBR. I just defined 4th partion entry to some dummy to prevent fdisk and similar to create new partition on unused space. Legacy OSes just ignore it.
Under Win7x-64 I use IMDISK to mount the hidden (undefined) NTFS partition, a bit rude with hardcoded offset but I don't expect to change partitions layout further...
imdisk -a -P -f \\.\PhysicalDrive1 -b 2199022206976 -x 63 -y 255 -o hd -m N:
Under WinXP it's not possible to enter 64b offset (exptected that)...

Linux is smart it already has offset option so I can just do
mount -o offset=$((512*4294965248)) /dev/sdb /mnt/n
or place in my /etc/fstab
/dev/sdb /mnt/n ntfs,iocharset=iso8859-2 loop,offset=2199022206976

---
DOS gives me freedom to unlimited HW access.

Complete thread:

• Partitioning of 4TB HDD for legacy OSes - RayeR, 27.04.2026, 22:45 (Users)
  • Partitioning of 4TB HDD for legacy OSes - mceric, 28.04.2026, 01:35
    • Partitioning of 4TB HDD for legacy OSes - bretjohn, 28.04.2026, 03:04
      • Partitioning of 4TB HDD for legacy OSes - Laaca, 28.04.2026, 05:08
        • Partitioning of 4TB HDD for legacy OSes - RayeR, 28.04.2026, 17:28
          • Partitioning of 4TB HDD for legacy OSes - Rugxulo, 29.04.2026, 05:23
            • Partitioning of 4TB HDD for legacy OSes - RayeR, 29.04.2026, 20:09
        • Partitioning of 4TB HDD for legacy OSes - bretjohn, 28.04.2026, 17:30
          • Partitioning of 4TB HDD for legacy OSes - Laaca, 28.04.2026, 18:31
            • Partitioning of 4TB HDD for legacy OSes - RayeR, 28.04.2026, 20:31
    • Partitioning of 4TB HDD for legacy OSes - RayeR, 28.04.2026, 17:21
  • Partitioning of 4TB HDD for legacy OSes - Zyzzle, 29.04.2026, 01:39
    • Partitioning of 4TB HDD for legacy OSes - bretjohn, 29.04.2026, 03:39
    • some TSR/patch to modify BIOS/EDD? - RayeR, 29.04.2026, 20:20
      • some TSR/patch to modify BIOS/EDD? - ecm, 29.04.2026, 20:56
        • some TSR/patch to modify BIOS/EDD? - RayeR, 30.04.2026, 17:31
          • some TSR/patch to modify BIOS/EDD? - ecm, 30.04.2026, 20:06
          • some TSR/patch to modify BIOS/EDD? - Laaca, 01.05.2026, 12:24
          • some TSR/patch to modify BIOS/EDD? - RayeR, 04.05.2026, 17:48
            • failed with hybrid MBR under Windows - RayeR, 07.05.2026, 15:40
              • failed with hybrid MBR under Windows - bretjohn, 07.05.2026, 22:36
                • failed with hybrid MBR under Windows - RayeR, 09.05.2026, 18:16
                  • failed with hybrid MBR under Windows - RayeR, 11.05.2026, 07:47
                    • New Idea how to beak 2TB on WinXP-32 - RayeR, 23.05.2026, 13:51