Rationale:

 - Right now:

   - These pages' Markdown will be rendered when browsing our
     repository in the GitLab web interface

   - The .md extension is more common nowadays: GitHub, GitLab, and various
     other major players have settled on it. Let's get used to it.

 - If we decide to migrate our blueprints to GitLab (#18079),
   this will be a necessary first step.

usb_install_and_upgrade/gpt.md

+[[!tag archived]]
+
+[[!toc levels=2]]
+
+GPT only, single partition
+==========================
+
+$ gdisk /dev/sdb
+
+1. o	create a new empty GUID partition table (GPT)
+2. n	add a new partition
+3. Partition number (1-128, default 1): 1
+4. First sector (34-3891166, default = 34) or {+-}size{KMGTP}: 
+
+Information: Moved requested sector from 34 to 2048 in
+order to align on 2048-sector boundaries.
+Use 'l' on the experts' menu to adjust alignment
+
+5. Last sector (2048-3891166, default = 3891166) or {+-}size{KMGTP}: 
+
+Current type is 'Linux/Windows data'
+
+6. Hex code or GUID (L to show codes, Enter = 0700): 
+
+Changed type of partition to 'Linux/Windows data'
+
+7. w	write table to disk and exit
+
+partprobe
+
+mkfs.vfat /dev/sdb1
+
+Result: Windows says the disk is not formated.
+
+GPT + Hybrid MBR, single partition
+==================================
+
+$ gdisk /dev/sdb
+
+1. o	create a new empty GUID partition table (GPT)
+2. x	extra functionality (experts only)
+3. l	set the sector alignment value
+4. Enter the sector alignment value (1-65536, default = 2048): 63
+5. m	return to main menu
+6. n	add a new partition
+7. Partition number (1-128, default 1): 1
+8. First sector (34-3891166, default = 34) or {+-}size{KMGTP}: 63
+9. Last sector (2048-3891166, default = 3891166) or {+-}size{KMGTP}: 
+
+Current type is 'Linux/Windows data'
+
+10. Hex code or GUID (L to show codes, Enter = 0700): 
+
+Changed type of partition to 'Linux/Windows data'
+
+11. r	recovery and transformation options (experts only)
+12. h	make hybrid MBR
+13. Type from one to three GPT partition numbers, separated by spaces, to be
+added to the hybrid MBR, in sequence: 1
+14. Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): N
+15. Enter an MBR hex code (default 07): 0c
+16. Set the bootable flag? (Y/N): N
+17. Unused partition space(s) found. Use one to protect more partitions? (Y/N): N
+18. w	write table to disk and exit
+
+	partprobe
+	mkfs.vfat /dev/sdb1
+
+Result: in the MBR, the first partition is the FAT32 one, which is
+detected and mounted by Windows.
+
+GPT + Hybrid MBR, single bootable partition
+===========================================
+
+Same steps as previously, but the bootable flag is set at step 15.
+After using liveusb-creator, the stick boots.
+
+
+GPT + Hybrid MBR, 3 partitions, 2nd one is bootable
+===================================================
+
+$ gdisk /dev/sdb
+
+1. o	create a new empty GUID partition table (GPT)
+2. x	extra functionality (experts only)
+3. l	set the sector alignment value
+4. Enter the sector alignment value (1-65536, default = 2048): 63
+5. m	return to main menu
+6. n	add a new partition
+7. Partition number (1-128, default 1): 1
+8. First sector (34-3891166, default = 34) or {+-}size{KMGTP}: 63
+9. Last sector (2048-3891166, default = 3891166) or {+-}size{KMGTP}: +64M
+10. Hex code or GUID (L to show codes, Enter = 0700): 
+
+Changed type of partition to 'Linux/Windows data'
+
+11. x	extra functionality (experts only)
+12. l	set the sector alignment value
+13. Enter the sector alignment value (1-65536, default = 2048): 2048
+14. m	return to main menu
+15. n	add a new partition
+16. Partition number (2-128, default 2): 2
+17. First sector (34-3891166, default = 131135) or {+-}size{KMGTP}: 
+
+Information: Moved requested sector from 131135 to 133120 in
+order to align on 2048-sector boundaries.
+
+18. Last sector (133120-3891166, default = 3891166) or {+-}size{KMGTP}: +1500M
+19. Hex code or GUID (L to show codes, Enter = 0700): 8301
+
+Changed type of partition to 'Linux reserved'
+
+20. n	add a new partition
+21. Partition number (3-128, default 3): 3
+22. First sector (34-3891166, default = 3205120) or {+-}size{KMGTP}: 
+23. Last sector (3205120-3891166, default = 3891166) or {+-}size{KMGTP}: 
+24. Hex code or GUID (L to show codes, Enter = 0700): 8301
+
+Changed type of partition to 'Linux reserved'
+
+25. x	extra functionality (experts only)
+26. a	set attributes
+27. Partition number (1-3): 2
+28. Toggle which attribute field (0-63, 64 or <Enter> to exit): 0
+29. Toggle which attribute field (0-63, 64 or <Enter> to exit): 2
+30. Toggle which attribute field (0-63, 64 or <Enter> to exit): 60
+31. Toggle which attribute field (0-63, 64 or <Enter> to exit): 62
+32. Toggle which attribute field (0-63, 64 or <Enter> to exit): 63
+
+Attribute value is D000000000000005. Set fields are:
+0 (system partition)
+2 (legacy BIOS bootable)
+60 (read-only)
+62 (hidden)
+63 (do not automount)
+
+33. Toggle which attribute field (0-63, 64 or <Enter> to exit):
+34. a	set attributes
+35. Partition number (1-3): 3
+36. Toggle which attribute field (0-63, 64 or <Enter> to exit): 63
+
+Attribute value is 8000000000000000. Set fields are:
+63 (do not automount)
+
+37. Toggle which attribute field (0-63, 64 or <Enter> to exit):
+38. r	recovery and transformation options (experts only)
+39. h	make hybrid MBR
+40. Type from one to three GPT partition numbers, separated by spaces, to be
+added to the hybrid MBR, in sequence: 1 2
+41. Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): N
+
+Creating entry for GPT partition #1 (MBR partition #1)
+
+42. Enter an MBR hex code (default 07): 0c
+43. Set the bootable flag? (Y/N): N
+
+Creating entry for GPT partition #2 (MBR partition #2)
+
+44. Enter an MBR hex code (default 83): 1c
+45. Set the bootable flag? (Y/N): Y
+46. Unused partition space(s) found. Use one to protect more partitions? (Y/N): Y
+47. Enter an MBR hex code (EE is EFI GPT, but may confuse MacOS): 0a
+48. w	write table to disk and exit
+
+	partprobe
+	mkfs.vfat /dev/sdb1
+	mkfs.vfat /dev/sdb2
+
+Use of liveusb-creator to install an ISO on `/dev/sdb2`.
+
+GPT + protective MBR, two partitions
+====================================
+
+	$ /sbin/sgdisk                      \
+	--clear                     \   # create a new partition table
+	--new=1:0:+1500M            \   # new partition 1, starts at begining, 1500 MiB size
+	--typecode=1:8301           \   # part 1, set type 8301 (Linux reserved)
+	--attributes=1:set:0        \   # part 1, set flag: system partition
+	--attributes=1:set:2        \   # part 1, set flag: legacy BIOS bootable
+        --attributes=1:set:60       \   # part 1, set flag: read-only
+        --attributes=1:set:62       \   # part 1, set flag: hidden
+        --attributes=1:set:63       \   # part 1, set flag: do not automount
+        --change-name=1:Linux       \   # part 1, change label to 'Linux'
+	--largest-new=2             \   # new partition, starts at begining, max size
+	--typecode=2:8301           \   # part 2, set type 8301 (Linux reserved)
+	--attributes=1:set:62       \   # part 2, set flag: hidden
+	--attributes=1:set:63       \   # part 2, set flag: do not automount
+	--change-name=2:persistent  \   # part 2, change label to 'persistent'
+	/dev/sdb
+
+Make the partition accessible to Windows, for the time of the installation:
+
+	<<EOF sed -e 's/^\([^#]*\) \+# .*$/\1/' | /sbin/gdisk /dev/sdb
+	r    # recovery and transformation options
+	h    # make hybrid MBR
+	1    # add first partition
+	N    # no EFI GPT (0xEE) partition
+	0c   # partition type (Win95 FAT32 LBA)
+	N    # don't set the bootable flag
+	N    # no protective partition
+	w    # write table to disk and exit
+	Y    # proceed, possibly destroying data
+	EOF
+
+
+Once the install has been done, lock things up:
+
+	<<EOF sed -e 's/^\([^#]*\) \+# .*$/\1/' | /sbin/gdisk /dev/sdb
+	x    # extra functionality
+	n    # create a new protective MBR
+	w    # write table to disk and exit
+	Y    # proceed, possibly destroying data
+	EOF