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/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.)

> 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/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.

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.