Le 05/04/2023 à 13:21, Ding, Shenghao a écrit :
Hi Both I wrote a test code to verify the be32_to_cpu & be32_to_cpup, static int __init lkm_init(void) { char test_buf[]={0x12, 0x34, 0xab, 0xbc, 0x56, 0x78, 0xef}; unsigned int *k, p, q; int i;
printk("Hello, Shanghai!\n");
for (i = 0; i < 4; i ++) { k = (unsigned int *)&test_buf[i]; p = be32_to_cpup((__be32 *)k); q = be32_to_cpu(test_buf[i]); printk("%d: *k = 0x%08x p = 0x%08x q = 0x%08x %ld\n", i, *k, p, q, sizeof(unsigned int)); } return 0; } The output is: [ 9109.722548] Hello, Shanghai! [ 9109.726287] 0: *k = 0xbcab3412 p = 0x1234abbc q = 0x12000000 4 [ 9109.727665] 1: *k = 0x56bcab34 p = 0x34abbc56 q = 0x34000000 4 [ 9109.728553] 2: *k = 0x7856bcab p = 0xabbc5678 q = 0xabffffff 4 [ 9109.729308] 3: *k = 0xef7856bc p = 0xbc5678ef q = 0xbcffffff 4 Apparently, be32_to_cpup's output is what I expected. Looking forward to your comments. Thanks.
Hi,
thanks for the clarification and code sample. You are right.
I had in mind that something like: be32_to_cpu((__be32 *)data); would make it. (thanks to the cast)
But because of the need of "&" and "[offset]", it would just make the code unnecessarily complex.
I think that your approach is better.
CJ