fullnet.blogg.se

Hex file crc 16 calculator checksum
Hex file crc 16 calculator checksum












hex file crc 16 calculator checksum
  1. #HEX FILE CRC 16 CALCULATOR CHECKSUM HOW TO#
  2. #HEX FILE CRC 16 CALCULATOR CHECKSUM CODE#
  3. #HEX FILE CRC 16 CALCULATOR CHECKSUM MAC#

  • It corresponds to the expected position of the field envfs_inode.size.
  • That value appears on the second output line.
  • finally, 524 bytes ( 522 rounded up to a multiple of 4) as a big character block.
  • then, four 4-byte chunks ( 16 bytes total), formatted as unsigned int, also on their own line.
  • first, seven 4-byte chunks ( 28 bytes total), formatted as unsigned int, on their own line.
  • Using hexdump with a more complex formatting string Assuming sizeof uint32_t is 32bits (4-bytes), that makes sizeof( envfs_super ) 28 bytes ( seven fields times four bytes each). There are exactly 44 bytes of binary data at the beginning of each *.env file. * The next inode follows after the data + padding to 4 byteįrom examining /usr/share/k1m0.env (which becomes the contents of partition 7) from factory firmware, it seems clear that k1m0.env begins with envfs_super followed immediately by envsfs_inode (much more follows). Uint32_t namelen /* The length of the filename _including_ a trailing 0 */Ĭhar data /* The filename (zero terminated) + padding to 4 byte boundary Uint32_t sb_crc /* crc for the superblock */ Uint32_t future /* reserved for future use */ * Superblock information at the beginning of the FS. #define ENVFS_MAGIC 0x798fba79 /* some random number */

    #HEX FILE CRC 16 CALCULATOR CHECKSUM CODE#

    all comments here are original to factory-supplied code (though re-aligned for readability below).It also shows how the bootloader validates the magic number and two different crc values found inside envfs_super, as well as an additional magic number found inside a struct of type envfs_inode (which itself is loaded from the bytes following envfs_super).įrom the file barebox-2011.06.0/include/envfs.h That file shows how a struct of type envfs_super is populated from the first few bytes of partition 7 (or 8). That string appears only in the file barebox-2011.06.0/commands/sataenv.c. Using an IDE (or grep), search within barebox-2011.06.0/ subdir inside WD GPL Source Code for the string wrong crc on env data. WHERE DOES "wrong crc on env data" OCCUR? the resulting k1m0.env passes crc validation during boot on actual hardware.edited only the two “crc” fields based on a modified k1m0.env (one byte of the content changed, size did not).the results are indistinguishable from the original, confirmed using hexdump (usage shown below).edited the four “size” and “crc” fields described below for an unmodified factory k1m0.env.Using the instructions in this guide, I have successfully The source code files referenced in this guide are found inside WD GPL Source Code available on the support downloads page.Ī binary representation of a struct named envfs_super and another struct named envfs_inode appear at the start of the kernel config partitions (required by bootloader) - thought process follows.

    #HEX FILE CRC 16 CALCULATOR CHECKSUM MAC#

    # - you can find the placeholder mac address by searching barebox source codeĬommandline:$console=ttyS0,115200n8, init=/sbin/init rootfstype=ext4 rw noinitrd mac_addr=00:11:22:33:44:55 model= serial= board_test= btn_status=0

    hex file crc 16 calculator checksum

    # - barebox appears to load a placeholder config if no config partitions pass crc # - notice how mac_addr is a bogus value and other values are blank Sataenv: partition 8 wrong crc on env data You may have landed here due to the following errors observed over UART during boot: sataenv: partition 7 wrong crc on env data

  • you are confident with commandline tools and their usage.
  • #HEX FILE CRC 16 CALCULATOR CHECKSUM HOW TO#

  • you know how to write kernel config to the appropriate partition(s).
  • you are able to examine WD-Supplied GPL Source Code to confirm the accuracy of the information here.
  • you are probably using UART to examine the device as it boots.
  • you have some insight about barebox bootloader.
  • This guide assumes an advanced use case for your WD M圜loud Gen1.
  • store new crc values to binary area of kernel config files.
  • store new length values to binary area of kernel config files.
  • hex file crc 16 calculator checksum

  • edit and null-pad kernel config, possibly changing its length.
  • analyze leading binary data within k1m0.env (partition 7) or k1m1.env (partition 8).
  • use files available in factory firmware (or firmware sq-*.deb archives).
  • WD M圜loud Gen1 (Comcerto CPU with Barebox bootloader) Computing New CRC and Size Values for Kernel Config Partitions














    Hex file crc 16 calculator checksum