On 08/01/2018 02:13 PM, Bin Meng wrote:
Hi,
Currently it seems that we have two CRC32 implementation in U-Boot. Two headers files are provided.
- include/linux/crc32.h
The implementation is drivers/mtd/ubi/crc32.c. Codes that use this implementation include:
drivers/mtd/ubi/* drivers/mtd/ubispl/* fs/ubifs/*
- include/u-boot/crc.h
The implementation is lib/crc32.c Codes that use this implementation include:
fs/btrfs/hash.c tools/* common/hash.c common/image.c common/image-fit.c lib/efi_loader/efi_boottime.c
It looks that include/linux/crc32.h was originally imported from Linux kernel's include/linux/crc32.h, but the implementation in Linux kernel's lib/crc32.c was not imported to U-Boot's lib/crc32.c but to drivers/mtd/ubi/crc32.c. Why?
Somehow U-Boot lib/crc32.c uses another different implementation from zlib.
This is a mess. For example if I include both headers in one C file, it won't compile.
Can we clean this up?
Thanks for pointing this out.
The drivers/mtd/ubi/crc32.c is based on an elder version of Linux.
When looking at the function signatures I am not happy with include/u-boot/crc.h uint32_t crc32 (uint32_t, const unsigned char *, uint) The last parameter should be size_t. Otherwise the CRC may be wrong on 64bit systems.
The two crc32 implementations do not have the same result on a low-endian system:
crc32_le(0, 'U-Boot', 6) = a289ac17 crc32(0, 'U-Boot', 6) = 134b0db4.
According to the comments in in include/linux/crc32.h the result of crc32_le is in bit reversed order.
Conflicting definitions could be avoided by removing #define crc32() in include/linux/crc32.h and adjusting the ubi code accordingly.
Best regards
Heinrich