mirror of
https://github.com/raspberrypi/rpi-eeprom.git
synced 2026-01-20 21:13:36 +08:00
1ba58068ea
If the size of bootconf.txt is reduced then set the unused data to all ones instead of leaving garbage at the end. The EEPROM header contains the actual file but this makes it easier to verify the image and makes overreads more obvious.
105 lines
3.7 KiB
Python
Executable File
105 lines
3.7 KiB
Python
Executable File
#!/usr/bin/python
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# rpi-eeprom-config
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# Utility for reading and writing the configuration file in the
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# Raspberry Pi4 bootloader EEPROM image.
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import argparse
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import struct
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import sys
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IMAGE_SIZE = 512 * 1024
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# Each section starts with a magic number followed by a 32 bit offset to the
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# next section (big-endian).
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# The number, order and size of the sections depends on the bootloader version
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# but the following mask can be used to test for section headers and skip
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# unknown data.
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MAGIC = 0x55aaf00f
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MAGIC_MASK = 0xfffff00f
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FILE_MAGIC = 0x55aaf11f # id for modifiable file, currently only bootconf.txt
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FILE_HDR_LEN = 20
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FILENAME_LEN = 12
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class BootloaderImage(object):
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def __init__(self, filename, output):
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self._filename = filename
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self._bytes = bytearray(open(filename, 'rb').read())
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self._out = None
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if output is not None:
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self._out = open(output, 'wb')
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if len(self._bytes) != IMAGE_SIZE:
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raise Exception("%s: Expected size %d bytes actual size %d bytes" %
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(filename, IMAGE_SIZE, len(self._bytes)))
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def find_config(self):
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offset = 0
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magic = 0
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while offset < IMAGE_SIZE:
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magic, length = struct.unpack_from('>LL', self._bytes, offset)
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if (magic & MAGIC_MASK) != MAGIC:
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raise Exception('EEPROM is corrupted')
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if magic == FILE_MAGIC: # Found a file
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name = self._bytes[offset + 8: offset + FILE_HDR_LEN]
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if name.decode('utf-8') == 'bootconf.txt':
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return (offset, length)
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offset += 4 + length
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offset += 8 - (offset % 8) # Pad
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raise Exception('Bootloader config not found')
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def write(self, new_config):
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hdr_offset, length = self.find_config()
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new_config_bytes = open(new_config, 'rb').read()
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new_len = len(new_config_bytes) + FILENAME_LEN + 4
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if new_len > length and new_len > 1024:
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raise Exception('Config is too large')
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if hdr_offset + len(new_config_bytes) + FILE_HDR_LEN > IMAGE_SIZE:
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raise Exception('EEPROM image size exceeded')
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struct.pack_into('>L', self._bytes, hdr_offset + 4, new_len)
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struct.pack_into(("%ds" % len(new_config_bytes)), self._bytes, hdr_offset + 4 + FILE_HDR_LEN, new_config_bytes)
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# If the new config is smaller than the old config then set any old
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# data which is now unused to all ones (erase value)
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pad_start = hdr_offset + 4 + FILE_HDR_LEN + len(new_config_bytes)
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pad = 0
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while pad < (length - len(new_config_bytes)):
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struct.pack_into('B', self._bytes, pad_start + pad, 0xff)
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pad = pad + 1
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if self._out is not None:
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self._out.write(self._bytes)
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self._out.close()
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else:
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sys.stdout.write(self._bytes)
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def read(self):
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hdr_offset, length = self.find_config()
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offset = hdr_offset + 4 + FILE_HDR_LEN
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config_bytes = self._bytes[offset:offset+length-FILENAME_LEN-4]
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if self._out is not None:
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self._out.write(config_bytes)
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self._out.close()
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else:
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sys.stdout.write(config_bytes)
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def main():
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parser = argparse.ArgumentParser('RPI EEPROM config tool')
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parser.add_argument('--config', help='Filename of new bootloader config')
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parser.add_argument('--out', help='Filename for the EEPROM image with updated config')
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parser.add_argument('eeprom', help='EEPROM filename (pieeprom.bin)')
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args = parser.parse_args()
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image = BootloaderImage(args.eeprom, args.out)
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if args.config is not None:
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image.write(args.config)
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else:
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image.read()
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if __name__ == '__main__':
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main()
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