[dpdk-dev] [PATCH v2 2/7] ether: do not mark ethernet address and header as packed

Bruce Richardson bruce.richardson at intel.com
Thu May 16 22:40:05 CEST 2019


On Thu, May 16, 2019 at 11:04:22AM -0700, Stephen Hemminger wrote:
> Since the Ethernet address and header are naturally aligned
> correctly on all architectures, there is no need to mark them
> as packed. This results in faster code, and also gets rid of
> warnings with gcc-9 about getting address of packed structure.
> 
> Suggested-by: Bruce Richardson <bruce.richardson at intel.com>
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---
>  lib/librte_net/rte_ether.h | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
> index ac8897681aca..0954d183cca7 100644
> --- a/lib/librte_net/rte_ether.h
> +++ b/lib/librte_net/rte_ether.h
> @@ -57,7 +57,7 @@ extern "C" {
>  struct ether_addr {
>  	/** Addr bytes in tx order */
>  	uint8_t addr_bytes[ETHER_ADDR_LEN] __rte_aligned(2);
> -} __attribute__((__packed__));
> +};
>  
>  #define ETHER_LOCAL_ADMIN_ADDR 0x02 /**< Locally assigned Eth. address. */
>  #define ETHER_GROUP_ADDR       0x01 /**< Multicast or broadcast Eth. address. */
> @@ -273,7 +273,7 @@ struct ether_hdr {
>  	struct ether_addr d_addr; /**< Destination address. */
>  	struct ether_addr s_addr; /**< Source address. */
>  	uint16_t ether_type;      /**< Frame type. */
> -} __attribute__((__packed__));
> +};
>  
>  /**
>   * Ethernet VLAN Header.
> @@ -283,7 +283,7 @@ struct ether_hdr {
>  struct vlan_hdr {
>  	uint16_t vlan_tci; /**< Priority (3) + CFI (1) + Identifier Code (12) */
>  	uint16_t eth_proto;/**< Ethernet type of encapsulated frame. */
> -} __attribute__((__packed__));
> +};
>  
>  /**
>   * VXLAN protocol header.
> @@ -293,7 +293,7 @@ struct vlan_hdr {
>  struct vxlan_hdr {
>  	uint32_t vx_flags; /**< flag (8) + Reserved (24). */
>  	uint32_t vx_vni;   /**< VNI (24) + Reserved (8). */
> -} __attribute__((__packed__));
> +};
>  
>  /* Ethernet frame types */
>  #define ETHER_TYPE_IPv4 0x0800 /**< IPv4 Protocol. */
> @@ -325,7 +325,7 @@ struct vxlan_gpe_hdr {
>  	uint8_t reserved[2]; /**< Reserved (16). */
>  	uint8_t proto;       /**< next-protocol (8). */
>  	uint32_t vx_vni;     /**< VNI (24) + Reserved (8). */
> -} __attribute__((__packed__));
> +};
>  

Are we sure that these last two structures are always 4-byte aligned in
packets?

>  /* VXLAN-GPE next protocol types */
>  #define VXLAN_GPE_TYPE_IPV4 1 /**< IPv4 Protocol. */
> -- 
> 2.20.1
> 


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