How do I calculate the CRC32 of u-boot header?

Installing and Using OpenWrt
1

I have the following router hardware: NBG-419N v2
I'm trying to flash openwrt to it, the web OEM way fails with a message: not a valid firmware
So I went ahead and tried the TFTP way, but in step 3 it says:

count new CRC32 of u-boot header (64 bytes) and write next 4 bytes (7A BE 7A CE for openwrt-18.06.5-ramips-rt305x-nbg-419n2-initramfs-kernel.bin)

Where does the "u-boot" header of 64bytes starts and ends? and how do I re-calculate it? (I used crc32 tool on linux, but I can't seem to get the right value, maybe I'm counting the wrong 64 bytes)

2

the header is at the start of the file
Clear the checksum by putting 00 00 00 00 in bytes 4-7
run crc32 over the header "64 bytes default"
the crc32 value will match the value that was in the checksum bytes 4-7
I use the windows "Hex Workshop" to do this

1 Like
3

yep that worked. I didn't know I had to reset the checksum to zero :slight_smile:

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