Function get_bootfs_vmo 

pub fn get_bootfs_vmo(
    zbi_vmo: &Vmo,
    check_crc: bool,
    log: &mut Log,
) -> Result<Vmo, Error>

Extracts the BOOTFS VMO from the ZBI VMO, mapping only the pages containing the STORAGE_BOOTFS item payload and decompressing it if needed.