mkinitcpio and bundled files' location

after passing files to mkinitcpio via FILES or BINARIES in mkinitcpio.conf, where exactly do they end up? let's say I added FILES=(/usr/lib/firmware/edid/abc.bin) for example, with the above line:

# mkinitcpio -p linux
...
==> Creating zstd-compressed initcpio image: '/boot/initramfs-linux.img'
==> Initcpio image generation successful
# cpio -t < /boot/initramfs-linux.img
early_cpio
kernel/
kernel/x86/
kernel/x86/microcode/
kernel/x86/microcode/AuthenticAMD.bin
# ???

how can I make sure the generate init file do contain the file? And how can I be certain of the path to pass to kernel parameters?