On Fri, May 04, 2007 at 03:27:53AM -0700, Clint Pachl wrote: > I'm curious if the flag bits, shown for each interface with ifconfig(8), > can be decoded in order to reveal the characteristics of NICs, such as > hardware RX/TX checksums and VLAN. > > So far I have searched: > > netintro(4) > ifmedia(4) > inet(4) > sys/net/if.c > sys/dev/pci/if_em.c > > But haven't found anything definitive. Can someone explain or point out > some source or man page?
ifconfig shows if_flags, it sounds like you are talking about if_capabilities however. In the case of em(4) grep tells us if_em.c: ifp->if_capabilities = IFCAP_VLAN_MTU; if_em.c: ifp->if_capabilities |= IFCAP_CSUM_TCPv4|IFCAP_CSUM_UDPv4; from net/if.h /* Capabilities that interfaces can advertise. */ #define IFCAP_CSUM_IPv4 0x00000001 /* can do IPv4 header csum */ #define IFCAP_CSUM_TCPv4 0x00000002 /* can do IPv4/TCP csum */ #define IFCAP_CSUM_UDPv4 0x00000004 /* can do IPv4/UDP csum */ #define IFCAP_IPSEC 0x00000008 /* can do IPsec */ #define IFCAP_VLAN_MTU 0x00000010 /* VLAN-compatible MTU */ #define IFCAP_VLAN_HWTAGGING 0x00000020 /* hardware VLAN tag support */ #define IFCAP_IPCOMP 0x00000040 /* can do IPcomp */ #define IFCAP_CSUM_TCPv6 0x00000080 /* can do IPv6/TCP checksums */ #define IFCAP_CSUM_UDPv6 0x00000100 /* can do IPv6/UDP checksums */ #define IFCAP_CSUM_TCPv4_Rx 0x00000200 /* can do IPv4/TCP (Rx only) */ #define IFCAP_CSUM_UDPv4_Rx 0x00000400 /* can do IPv4/UDP (Rx only) */ I don't think this is exported to userland, it is the kind of thing that should be transparent to the user and perhaps mentioned in a man page if appropriate.
