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#!/usr/bin/env python3
"""
# SPDX-License-Identifier: GPL-2.0-or-later
#
# sercomm-kernel-header.py: Creates Sercomm kernel header
#
# Copyright © 2022 Mikhail Zhilkin
"""
import argparse
import binascii
import os
import struct
KERNEL_HEADER_SIZE = 0x100
PADDING = 0xff
ROOTFS_FAKE_HEADER = "UBI#"
def auto_int(x):
return int(x, 0)
def create_kernel_header(args):
out_file = open(args.header_file, "wb")
header = get_kernel_header(args)
out_file.write(header)
out_file.close()
def get_kernel_header(args):
header = bytearray([PADDING] * KERNEL_HEADER_SIZE)
struct.pack_into('<L', header, 0xc, 0xffffff02)
struct.pack_into('<L', header, 0x1c, 0x0)
struct.pack_into('<L', header, 0x34, 0x0)
struct.pack_into('<L', header, 0x10, args.kernel_offset)
struct.pack_into('<L', header, 0x28, args.rootfs_offset)
if (args.rootfs_file):
if (args.rootfs_checking_size):
rootfs_size = args.rootfs_checking_size
else:
rootfs_size = os.path.getsize(args.rootfs_file)
buf = open(args.rootfs_file,'rb').read(rootfs_size)
crc = binascii.crc32(buf) & 0xffffffff
else:
rootfs_size = len(ROOTFS_FAKE_HEADER)
crc = binascii.crc32(str.encode(ROOTFS_FAKE_HEADER)) & \
0xffffffff
struct.pack_into('<L', header, 0x2c, rootfs_size)
struct.pack_into('<L', header, 0x30, crc)
rootfs_end_offset = args.rootfs_offset + rootfs_size
struct.pack_into('<L', header, 0x4, rootfs_end_offset)
kernel_size = os.path.getsize(args.kernel_file)
struct.pack_into('<L', header, 0x14, kernel_size)
buf = open(args.kernel_file,'rb').read()
crc = binascii.crc32(buf) & 0xffffffff
struct.pack_into('<L', header, 0x18, crc)
crc = binascii.crc32(header) & 0xffffffff
struct.pack_into('<L', header, 0x8, crc)
struct.pack_into('<L', header, 0x0, 0x726553)
return header
def main():
global args
parser = argparse.ArgumentParser(description='This script generates \
a kernel header for the Sercomm mt7621 devices')
parser.add_argument('--kernel-image',
dest='kernel_file',
action='store',
type=str,
help='Path to a Kernel binary image')
parser.add_argument('--kernel-offset',
dest='kernel_offset',
action='store',
type=auto_int,
help='Kernel offset')
parser.add_argument('--rootfs-offset',
dest='rootfs_offset',
action='store',
type=auto_int,
help='RootFS offset')
parser.add_argument('--output-header',
dest='header_file',
action='store',
type=str,
help='Output kernel header file')
parser.add_argument('--rootfs-image',
dest='rootfs_file',
action='store',
type=str,
help='Path to RootFS binary image (optional)')
parser.add_argument('--rootfs-checking-size',
dest='rootfs_checking_size',
action='store',
type=auto_int,
help='Bytes count for CRC calculation (optional)')
args = parser.parse_args()
if ((not args.kernel_file) or
(not args.kernel_offset) or
(not args.rootfs_offset) or
(not args.header_file)):
parser.print_help()
exit()
create_kernel_header(args)
main()
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