Hi Zoltan, On 03/24/2015 06:42 PM, Zoltan Kiss wrote: > Hi, > > I've noticed in lib/netdev-dpdk.c that __rte_pktmbuf_init() stores the > packet metadata right after "struct rte_mbuf", and before the buffer data: > > /* start of buffer is just after mbuf structure */ > m->buf_addr = (char *)m + sizeof(struct dp_packet); > > (struct dp_packet has the rte_mbuf as first member if DPDK enabled) > > However, lib/librte_mbuf/rte_mbuf.h seems to codify that the buffer > should start right after the rte_mbuf: > > /** > * Given the buf_addr returns the pointer to corresponding mbuf. > */ > #define RTE_MBUF_FROM_BADDR(ba) (((struct rte_mbuf *)(ba)) - 1) > > /** > * Given the pointer to mbuf returns an address where it's buf_addr > * should point to. > */ > #define RTE_MBUF_TO_BADDR(mb) (((struct rte_mbuf *)(mb)) + 1) > > These macros are used for attaching/detaching mbuf's to each other. This > is the way the code retrieves the direct buffer from an indirect one, > and vica versa. I think if we want to keep the metadata feature (which I > guess is quite important), we need to add a pointer to rte_mbuf, which > helps the direct and indirect structs to find each other. Something like: > > struct rte_mbuf *attach; /**< Points to the other buffer if this > one > is (in)direct. Otherwise NULL. */ > > What do you think?
I've just sent a patch that should fix this issue. http://dpdk.org/ml/archives/dev/2015-March/015722.html Let me know if you have any comment on it. Regards, Olivier
