3 ms·

Even Windows has a separate, NTFS boot partition these days. Fail to see the point of this, and since the main take basically is "put your /boot inside the FAT

Even Windows has a separate, NTFS boot partition these days. Fail to see the point of this, and since the main take basically is "put your /boot inside the FAT ESP, or if not possible, make /boot a FAT partition", it's also bound to create a lot of disagreement.

ChuckNorris89 4y ago
Does it? On my Windows 11 install, the EFI partition is still FAT32. There are no other partitions than the C and the recovery partition. Am I missing something?
- CameronNemo 4y ago
  The commenter is saying that there is an NTFS boot partition that is chained after the ESP. So UEFI mounts and execs whatever is in the (vFAT) ESP, and then that ESP bootloader loads data from the (NTFS) boot partition.
  - vetinari 4y ago
    MSR (that another partition) has no role in Windows boot. Windows will work without it being present at all.
- p_l 4y ago
  Windows has been setting up Reserved partitions with boot code for some time now - even (or especially) on systems without EFI
  - deathanatos 4y ago
    The OP is about a separate boot partition, which is normally where the kernel and associated data (on Linux, an initramfs, obviously Windows would differ a bit). The "Reserved" partition on Windows machines isn't really a boot partition, for any meaningful definition of it. It's just … reserved, and MS being MS. On my machine, it's empty (unformatted, all 0s). It is lightly documented here: https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions?view=windows-11#microsoft-reserved-partition-msr https://learn.microsoft.com/en-us/windows-hardware/manufactu... (I'd expect your typical GPT Windows install to have about four partitions: the ESP, the empty "reserved" partition, a recovery partition, and the main NTFS partition.)
    - cesarb 4y ago
      > The "Reserved" partition on Windows machines isn't really a boot partition, for any meaningful definition of it. It's just … reserved, and MS being MS. On my machine, it's empty (unformatted, all 0s). It is lightly documented here: https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions?view=windows-11#microsoft-reserved-partition-msr https://learn.microsoft.com/en-us/windows-hardware/manufactu... IIRC, that "reserved" partition is to allow converting the data partition which follows it to a "dynamic disk" (which AFAIK, is Microsoft's equivalent to a Linux LVM PV). That conversion needs to grow the partition backwards to prepend some headers, and that extra space comes from shrinking the reserved partition just before it.
    - p_l 4y ago
      On various BIOS-based systems, the reserved partition would contain files necessary for booting windows from its system volume, bridging the gap between what could be accessed by simplistic MBR boot code, the NTFS boot code block, and the NTFS-understanding, ARC emulating (for NT5) or EFI-emulating (NT6) boot system that would load target system. Details on whether reserved partition would be created and what would be on it depend on hardware you're installing on, and if separate boot partition is necessary windows installer would inform you about need to create an extra partition.
vetinari 4y ago
Windows does not have a separate NTFS boot partition. MSR is not it (check the size and content). Windows Boot Manager and BCD are stored on the EFI partition. Windows Boot Manager itself does understand NTFS: it loads winload.efi, ntoskrnl.exe and core drivers from the system root itself. This way, Windows is not going to have the common linux problem ("update failed, /boot too small"). Two partitions are needed only for Bitlocker; one has to be unencrypted. Similarly with Apple: they use APFS subvolume for boot files. They do not bother with multiple partitions and static allocations, guessing, what size is going to be OK. They can use as much or as little space as they need. -- With Linux, I've been using btrfs subvolume for /boot. It works with "normal" distributions, grub complains (it cannot write there; I find that OK). The dynamic nature of the space used is great. It doesn't work with ostree-based distributions (Fedora Silverblue & its ilk); ostree cannot generate proper BLS and grub.cfg for subvolumes.
- AshamedCaptain 4y ago
  I'm talking about the WinRE partition, which is required to boot Bitlocker encrypted boot partition (and Bitlocker is enabled by default). Enabling Bitlocker without one results in an error message, and Windows happily recreates/resizes the WinRE partition on every (OS) upgrade by simply reducing the size of the main partition. It has been a long time that the size of the ESP is not enough for all the stuff that Windows wants to do on preboot. For the record, and showing again the unfairness of the entire MS monopoly situation, most commercial UEFI implementations out there happen to understand NTFS. This allows e.g. a Windows pendrive to boot no matter how the user formats it.

ChuckNorris89 4y ago

Does it? On my Windows 11 install, the EFI partition is still FAT32. There are no other partitions than the C and the recovery partition. Am I missing something?

CameronNemo 4y ago
The commenter is saying that there is an NTFS boot partition that is chained after the ESP. So UEFI mounts and execs whatever is in the (vFAT) ESP, and then that ESP bootloader loads data from the (NTFS) boot partition.
- vetinari 4y ago
  MSR (that another partition) has no role in Windows boot. Windows will work without it being present at all.
p_l 4y ago
Windows has been setting up Reserved partitions with boot code for some time now - even (or especially) on systems without EFI
- deathanatos 4y ago
  The OP is about a separate boot partition, which is normally where the kernel and associated data (on Linux, an initramfs, obviously Windows would differ a bit). The "Reserved" partition on Windows machines isn't really a boot partition, for any meaningful definition of it. It's just … reserved, and MS being MS. On my machine, it's empty (unformatted, all 0s). It is lightly documented here: https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions?view=windows-11#microsoft-reserved-partition-msr https://learn.microsoft.com/en-us/windows-hardware/manufactu... (I'd expect your typical GPT Windows install to have about four partitions: the ESP, the empty "reserved" partition, a recovery partition, and the main NTFS partition.)
  - cesarb 4y ago
    > The "Reserved" partition on Windows machines isn't really a boot partition, for any meaningful definition of it. It's just … reserved, and MS being MS. On my machine, it's empty (unformatted, all 0s). It is lightly documented here: https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions?view=windows-11#microsoft-reserved-partition-msr https://learn.microsoft.com/en-us/windows-hardware/manufactu... IIRC, that "reserved" partition is to allow converting the data partition which follows it to a "dynamic disk" (which AFAIK, is Microsoft's equivalent to a Linux LVM PV). That conversion needs to grow the partition backwards to prepend some headers, and that extra space comes from shrinking the reserved partition just before it.
  - p_l 4y ago
    On various BIOS-based systems, the reserved partition would contain files necessary for booting windows from its system volume, bridging the gap between what could be accessed by simplistic MBR boot code, the NTFS boot code block, and the NTFS-understanding, ARC emulating (for NT5) or EFI-emulating (NT6) boot system that would load target system. Details on whether reserved partition would be created and what would be on it depend on hardware you're installing on, and if separate boot partition is necessary windows installer would inform you about need to create an extra partition.

vetinari 4y ago

Windows does not have a separate NTFS boot partition. MSR is not it (check the size and content). Windows Boot Manager and BCD are stored on the EFI partition. Windows Boot Manager itself does understand NTFS: it loads winload.efi, ntoskrnl.exe and core drivers from the system root itself. This way, Windows is not going to have the common linux problem ("update failed, /boot too small"). Two partitions are needed only for Bitlocker; one has to be unencrypted. Similarly with Apple: they use APFS subvolume for boot files. They do not bother with multiple partitions and static allocations, guessing, what size is going to be OK. They can use as much or as little space as they need. -- With Linux, I've been using btrfs subvolume for /boot. It works with "normal" distributions, grub complains (it cannot write there; I find that OK). The dynamic nature of the space used is great. It doesn't work with ostree-based distributions (Fedora Silverblue & its ilk); ostree cannot generate proper BLS and grub.cfg for subvolumes.

AshamedCaptain 4y ago
I'm talking about the WinRE partition, which is required to boot Bitlocker encrypted boot partition (and Bitlocker is enabled by default). Enabling Bitlocker without one results in an error message, and Windows happily recreates/resizes the WinRE partition on every (OS) upgrade by simply reducing the size of the main partition. It has been a long time that the size of the ESP is not enough for all the stuff that Windows wants to do on preboot. For the record, and showing again the unfairness of the entire MS monopoly situation, most commercial UEFI implementations out there happen to understand NTFS. This allows e.g. a Windows pendrive to boot no matter how the user formats it.