> From: Morten Brørup [mailto:m...@smartsharesystems.com] > Sent: Sunday, 13 October 2024 10.36 > > Ethernet packets can be VLAN tagged, i.e. an Ethernet header can have a > VLAN tag (a.k.a. VLAN header) embedded. > Since the Ethernet header is 2 byte aligned, and the VLAN tag is > directly > related to the Ethernet header, the VLAN tag is also 2 byte aligned, so > packing the VLAN tag structure is not necessary.
Stephen, Bruce, you missed the VLAN header type in this patch: https://git.dpdk.org/dpdk/commit/lib/librte_net/rte_ether.h?id=da5350ef29afd35c1adabe76f60832f3092269ad This patch completes your work. > > Furthermore, the Ethernet header type is implictly 2 byte aligned, so > removed the superfluous explicit 2 byte alignment. > > Added static_asserts to verify the size and alignment of the various > Ethernet types. > > Signed-off-by: Morten Brørup <m...@smartsharesystems.com> > --- > lib/net/rte_ether.h | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/lib/net/rte_ether.h b/lib/net/rte_ether.h > index 403e84f50b..c9a0b536c3 100644 > --- a/lib/net/rte_ether.h > +++ b/lib/net/rte_ether.h > @@ -11,6 +11,8 @@ > * Ethernet Helpers in RTE > */ > > +#include <assert.h> > +#include <stdalign.h> > #include <stdint.h> > #include <stdio.h> > > @@ -75,6 +77,11 @@ struct __rte_aligned(2) rte_ether_addr { > uint8_t addr_bytes[RTE_ETHER_ADDR_LEN]; /**< Addr bytes in tx > order */ > }; > > +static_assert(sizeof(struct rte_ether_addr) == 6, > + "sizeof(struct rte_ether_addr) == 6"); > +static_assert(alignof(struct rte_ether_addr) == 2, > + "alignof(struct rte_ether_addr) == 2"); > + > #define RTE_ETHER_LOCAL_ADMIN_ADDR 0x02 /**< Locally assigned Eth. > address. */ > #define RTE_ETHER_GROUP_ADDR 0x01 /**< Multicast or broadcast Eth. > address. */ > > @@ -290,12 +297,17 @@ rte_ether_unformat_addr(const char *str, struct > rte_ether_addr *eth_addr); > * Ethernet header: Contains the destination address, source address > * and frame type. > */ > -struct __rte_aligned(2) rte_ether_hdr { > +struct rte_ether_hdr { > struct rte_ether_addr dst_addr; /**< Destination address. */ > struct rte_ether_addr src_addr; /**< Source address. */ > rte_be16_t ether_type; /**< Frame type. */ > }; > > +static_assert(sizeof(struct rte_ether_hdr) == 14, > + "sizeof(struct rte_ether_hdr) == 14"); > +static_assert(alignof(struct rte_ether_hdr) == 2, > + "alignof(struct rte_ether_hdr) == 2"); > + > /** > * Ethernet VLAN Header. > * Contains the 16-bit VLAN Tag Control Identifier and the Ethernet > type > @@ -304,7 +316,12 @@ struct __rte_aligned(2) rte_ether_hdr { > struct rte_vlan_hdr { > rte_be16_t vlan_tci; /**< Priority (3) + CFI (1) + Identifier > Code (12) */ > rte_be16_t eth_proto; /**< Ethernet type of encapsulated frame. > */ > -} __rte_packed; > +}; > + > +static_assert(sizeof(struct rte_vlan_hdr) == 4, > + "sizeof(struct rte_vlan_hdr) == 4"); > +static_assert(alignof(struct rte_vlan_hdr) == 2, > + "alignof(struct rte_vlan_hdr) == 2"); > > > > -- > 2.43.0
