Maybe *data is not a printable character?
On Fri, Jun 30, 2017 at 12:54 PM, MD I. Islam <tamim@xxxxxxxxxxx> wrote:
> Hi
>
> I have following code attached to an interface:
>
> SEC("simple")
> int handle_ingress(struct __sk_buff *skb)
> {
> unsigned char *data = (unsigned char *)(long)skb->data;
> char fmt[] = "%u\n";
> bpf_trace_printk(fmt, sizeof(fmt), *data);
> return 0;
> }
>
> When packets pass through the interface, it does not print anything at
> /sys/kernel/debug/tracing/trace_pipe. However if I do
> bpf_trace_printk(fmt, sizeof(fmt), data), it prints the pointer. Could
> you please advise what is wrong here?
>
> Many thanks
> Tamim
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