> From: David Marchand [mailto:[email protected]] > Sent: Tuesday, 4 November 2025 14.59 > > On Tue, 4 Nov 2025 at 11:02, David Marchand <[email protected]> > wrote: > > > > When debugging TSO and other checksum offloads, dumping the various > > l*_len fields and TSO segmentation size can be helpful. > > > > Example in OVS that dumps a mbuf on rte_eth_tx_prepare failure: > > > > Before: > > netdev_dpdk(pmd-c30/id:11)|DBG|dpdk0: First invalid packet: > > dump mbuf at 0x2201a916c0, iova=0x2200800580, buf_len=6864 > > pkt_len=6804, ol_flags=0x3114800000000102, nb_segs=1, port=65535, > ptype=0 > > segment at 0x2201a916c0, data=0x22008005b2, len=6804, off=50, > refcnt=1 > > Dump data at [0x22008005b2], len=6804 > > ... > > > > After: > > netdev_dpdk(pmd-c30/id:11)|DBG|dpdk0: First invalid packet: > > dump mbuf at 0x2201a916c0, iova=0x2200800580, buf_len=6864, > pkt_len=6804 > > outer_l2_len=14, outer_l3_len=40, l2_len=38, l3_len=40, l4_len=32 > > ol_flags=0x3114800000000102, nb_segs=1, port=65535, ptype=0 > > segment at 0x2201a916c0, data=0x22008005b2, len=6804, off=50, > refcnt=1 > > Dump data at [0x22008005b2], len=6804 > > ... > > > > Signed-off-by: David Marchand <[email protected]> > > --- > > lib/mbuf/rte_mbuf.c | 41 +++++++++++++++++++++++++++++++++++++---- > > 1 file changed, 37 insertions(+), 4 deletions(-) > > > > diff --git a/lib/mbuf/rte_mbuf.c b/lib/mbuf/rte_mbuf.c > > index 0d931c7a15..12710a59df 100644 > > --- a/lib/mbuf/rte_mbuf.c > > +++ b/lib/mbuf/rte_mbuf.c > > @@ -750,10 +750,43 @@ rte_pktmbuf_dump(FILE *f, const struct rte_mbuf > *m, unsigned dump_len) > > > > __rte_mbuf_sanity_check(m, 1); > > > > - fprintf(f, "dump mbuf at %p, iova=%#" PRIx64 ", > buf_len=%u\n", m, rte_mbuf_iova_get(m), > > - m->buf_len); > > - fprintf(f, " pkt_len=%u, ol_flags=%#"PRIx64", nb_segs=%u, > port=%u", > > - m->pkt_len, m->ol_flags, m->nb_segs, m->port); > > + fprintf(f, "dump mbuf at %p, iova=%#" PRIx64 ", buf_len=%u, > pkt_len=%u\n", > > + m, rte_mbuf_iova_get(m), m->buf_len, m->pkt_len); > > + if (m->ol_flags & RTE_MBUF_F_TX_OFFLOAD_MASK) { > > + const char *sep = ""; > > + > > + fprintf(f, " "); > > + if (m->outer_l2_len != 0) { > > + fprintf(f, "%souter_l2_len=%u", sep, m- > >outer_l2_len); > > One more round will be needed for MSVC (CI did not report it on v1, > some tests did not run..). > ../lib/mbuf/rte_mbuf.c(760): error C2220: the following warning is > treated as an error > ../lib/mbuf/rte_mbuf.c(760): warning C4477: 'fprintf' : format string > '%u' requires an argument of type 'unsigned int', but variadic > argument 2 has type 'const uint64_t' > ../lib/mbuf/rte_mbuf.c(760): note: consider using '%llu' in the format > string > ../lib/mbuf/rte_mbuf.c(760): note: consider using '%Iu' in the format > string > ../lib/mbuf/rte_mbuf.c(760): note: consider using '%I64u' in the format > string > > This is probably because of the bitfields we have for the tx_offload > field. > lib/mbuf/rte_mbuf_core.h: RTE_MBUF_L2_LEN_BITS = 7, > lib/mbuf/rte_mbuf_core.h: RTE_MBUF_L3_LEN_BITS = 9, > lib/mbuf/rte_mbuf_core.h: RTE_MBUF_L4_LEN_BITS = 8, > lib/mbuf/rte_mbuf_core.h: RTE_MBUF_OUTL3_LEN_BITS = 9, > lib/mbuf/rte_mbuf_core.h: RTE_MBUF_OUTL2_LEN_BITS = 7, > lib/mbuf/rte_mbuf_core.h: uint64_t > l2_len:RTE_MBUF_L2_LEN_BITS; > lib/mbuf/rte_mbuf_core.h: uint64_t > l3_len:RTE_MBUF_L3_LEN_BITS; > lib/mbuf/rte_mbuf_core.h: uint64_t > l4_len:RTE_MBUF_L4_LEN_BITS; > lib/mbuf/rte_mbuf_core.h: uint64_t > outer_l3_len:RTE_MBUF_OUTL3_LEN_BITS; > lib/mbuf/rte_mbuf_core.h: uint64_t > outer_l2_len:RTE_MBUF_OUTL2_LEN_BITS; > > > Passing %PRIu64 instead of %u breaks build with gcc and clang. > ../lib/mbuf/rte_mbuf.c: In function ‘rte_pktmbuf_dump’: > ../lib/mbuf/rte_mbuf.c:760:36: error: format ‘%lu’ expects argument of > type ‘long unsigned int’, but argument 4 has type ‘int’ > [-Werror=format=] > 760 | fprintf(f, "%souter_l2_len=%"PRIu64, sep, m->outer_l2_len); > | ^~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ > | | > | int >
Interesting difference in interpretation between the compilers. > > I'll go with simple casting, like: > + fprintf(f, "%souter_l2_len=%u", sep, (unsigned > int)m->outer_l2_len); Agree. > > > -- > David Marchand
