cksm
csum = (__force unsigned int)cksm(reipl_block_actual, reipl_block_actual->hdr.len, 0);
csum = (__force u32)cksm(buf_align, size, 0);
return (__force u32)cksm(&os_info->version_major, size, 0);
os_info.entry[nr].csum = (__force u32)cksm(ptr, size, 0);
return cksm(src, len, sum);