[Bug 769669] Re: selecting efi partition overwrites windows bootloader

[Keshav]

Also the installer should use FAT32 instead of FAT16 for EFI SYSTEM
PARTITION as mandated by the UEFI Spec. FAT16 ESP partition is not
recognised by Windows UEFI bootloader because of this.

The below quote is copied form the UEFI Specification 2.3.1 - Chapter
12.3 File System Format.

[QUOTE]
EFI encompasses the use of FAT32 for a system partition, and FAT12 or FAT16 for removable media. The FAT32 system partition is identified by an OSType value other than that used to identify previous versions of FAT. This unique partition type distinguishes an EFI defined file system from a normal FAT file system. The file system supported by EFI includes support for long file names.

FAT defines that all files in a directory must have a unique name, and
unique is defined as a case insensitive match.

UEFI does not impose a restriction on the number or location of System Partitions that can exist on a system. System Partitions are discovered when required by UEFI firmware by examining the partition GUID and verifying that the contents of the partition conform to the FAT file system as defined in Section 12.3.1.1. Further, UEFI implementations may allow the use of conforming FAT partitions which do not use the ESP GUID. Partition creators may prevent UEFI firmware from examining and using a specific partition by setting bit 1 of the Partition Attributes (see 5.3.3) which will exclude the partition as a potential ESP. 
[/QUOTE]

The installer should also reuse the existing filesystem if a valid FAT32
EFISYS partition is selected during installation instead simply
formatting the partition to FAT16.

** Summary changed:

- selecting efi partition overwrites windows bootloader
+ Installer should not format an existing EFI SYSTEM PARTITION and should use FAT32 instead of FAT16 as the FS

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https://bugs.launchpad.net/bugs/769669

Title:
  Installer should not format an existing EFI SYSTEM PARTITION and
  should use FAT32 instead of FAT16 as the FS

Status in “partman-efi” package in Ubuntu:
  New

Bug description:
  Binary package hint: partman-efi

  When selecting an EFI partition under parted during ubiquity install
  on 11.04, there is no option to select mount point.  As windows 7 had
  installed an EFI partition at /dev/sda1 formatted to NTFS, I selected
  that.  I did not select that it should format the mount point, but it
  did anyway to FAT16 and deleted the windows bootloader.  Update-grub
  does not find windows, and I had to go to great lengths to reinstall
  the bootloader to the same partition as windows, it is still missing
  from /dev/sda.

  I had expected that even if /dev/sda1 was formatted, it would at least
  preserve the existing bootloader instead of putting me in a position
  where I had to use a windows recovery disk for several hours until I
  can now at least boot to windows using the bios, but grub is still
  unaware of the windows install.  I expected windows to overwrite grub,
  but I didn't expect installing linux to break my windows install.

  I encountered this bug after having the problems in this bug:
  https://bugs.launchpad.net/bugs/765270.

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