Hello,
I was recently working through the xdp tutorial and in the
packet01-parsing lesson the sizeof a pointer to the ethernet header
struct is used, not the sizeof the struct itself[0]. I peeked and the
solution for this section also still uses the sizeof a pointer and not
the struct so this isn't part of the tutorial and I was wondering what
is going on? I don't think the verifier is re-writing these addresses,
only those for the memory access into the packet data.
#include <stdio.h>
#include <linux/if_ether.h>
int main(void)
{
struct ethhdr normal = {0};
struct ethhdr *eth_hdr_ptr;
printf("Size of struct %lu\n",sizeof(normal)); // prints 14
printf("Size of struct pointer %lu\n",sizeof(eth_hdr_ptr)); //
prints 8
return 0;
}
[0]https://github.com/xdp-project/xdp-tutorial/blob/master/packet01-parsing/xdp_prog_kern.c#L34
--
Logan
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