Matching crc32 checksums from kernel and user space
Kalle Valo
kvalo at qca.qualcomm.com
Mon Nov 16 07:27:21 PST 2015
Kalle Valo <kvalo at qca.qualcomm.com> writes:
> Hi,
>
> I want ath10k to print a checksum for the firmware image and include
> that to the firmware crash dump file as well. Then I want to print the
> same checksum from user space scripts and verify it with the crash dump
> file.
>
> I thought that crc32 would be good enough for me but it wasn't that
> simple as I can't seem to getting matching checksums, at least not with
> the user space tools I found. For a test case I created a simple file:
>
> $ xxd /lib/firmware/ath10k/crc-test.bin
> 00000000: 3132 3334 3536 3738 3930 0a 1234567890.
>
> In kernel I get these checksums:
>
> [ 574.867724] crc32_le(0) 8916bc26
> [ 574.867739] crc32_le(~0) 1d6ef235
> [ 574.867743] crc32_be(0) b9346a4c
> [ 574.867746] crc32_be(~0) 71467465
>
> And from python I got (value in parenthesis is the seed I used):
>
> binascii.crc32(00000000) 0xe2910dcaL
> binascii.crc32(ffffffff) 0x76e943d9L
Johannes Berg pointed out that this looks to be a sign issue, I just
need to invert the python value and then I get the same value:
>>> hex(~0x76e943d9 & 0xffffffff)
'0x8916bc26'
--
Kalle Valo
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