Raspberry Pi OS Bookworm keeps the FAT boot partition at /boot/firmware, where
the raspi-firmware post-update hook syncs the initramfs. Binding it at /boot in
the chroot sent update-initramfs's output to the ext4 root, so the firmware
booted a stock initramfs without cryptsetup -> (initramfs) emergency shell, no
LUKS prompt. boot_bind_target() detects the layout and binds (and unmounts) the
FAT at the right place; legacy single-FAT layouts still use /boot.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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