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| author | Michael Brown | 2011-05-05 19:02:44 +0200 |
|---|---|---|
| committer | Michael Brown | 2011-05-05 19:10:31 +0200 |
| commit | c1cc769ef4661f121cd7664f7d8fa4bd06dde005 (patch) | |
| tree | 6e71bd7e992406a82094a7b70b33474dcea1286c /src/net/ipv4.c | |
| parent | [bofm] Pass BOFM version 2 table to SetStatus() if applicable (diff) | |
| download | ipxe-c1cc769ef4661f121cd7664f7d8fa4bd06dde005.tar.gz ipxe-c1cc769ef4661f121cd7664f7d8fa4bd06dde005.tar.xz ipxe-c1cc769ef4661f121cd7664f7d8fa4bd06dde005.zip | |
[ipv4] Include network device metadata in packet traces
(Ab)use the "ident" field in transmitted IPv4 packets to convey
metadata about the network device. In particular:
bits 0-3 represent the low bits of the "RX" good packet counter
bits 4-7 represent the low bits of the "RXE" bad packet counter
bits 8-15 represent the transmitted packet sequence number
This allows some relevant information about the internal state of the
network device to be read out from a packet trace from a non-debug
build of iPXE. In particular, it allows a packet trace containing
packets transmitted by iPXE to indicate whether or not any packets
have been received by iPXE.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/net/ipv4.c')
| -rw-r--r-- | src/net/ipv4.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/src/net/ipv4.c b/src/net/ipv4.c index b2d51ada..465df45e 100644 --- a/src/net/ipv4.c +++ b/src/net/ipv4.c @@ -23,8 +23,8 @@ FILE_LICENCE ( GPL2_OR_LATER ); -/* Unique IP datagram identification number */ -static uint16_t next_ident = 0; +/* Unique IP datagram identification number (high byte) */ +static uint8_t next_ident_high = 0; /** List of IPv4 miniroutes */ struct list_head ipv4_miniroutes = LIST_HEAD_INIT ( ipv4_miniroutes ); @@ -314,7 +314,6 @@ static int ipv4_tx ( struct io_buffer *iobuf, iphdr->verhdrlen = ( IP_VER | ( sizeof ( *iphdr ) / 4 ) ); iphdr->service = IP_TOS; iphdr->len = htons ( iob_len ( iobuf ) ); - iphdr->ident = htons ( ++next_ident ); iphdr->ttl = IP_TTL; iphdr->protocol = tcpip_protocol->tcpip_proto; iphdr->dest = sin_dest->sin_addr; @@ -335,6 +334,14 @@ static int ipv4_tx ( struct io_buffer *iobuf, goto err; } + /* (Ab)use the "ident" field to convey metadata about the + * network device statistics into packet traces. Useful for + * extracting debug information from non-debug builds. + */ + iphdr->ident = htons ( ( (++next_ident_high) << 8 ) | + ( ( netdev->rx_stats.bad & 0xf ) << 4 ) | + ( ( netdev->rx_stats.good & 0xf ) << 0 ) ); + /* Determine link-layer destination address */ if ( ( rc = ipv4_ll_addr ( next_hop, iphdr->src, netdev, ll_dest ) ) != 0 ) { |