32bit libpcap failure on Linux-ppc64 machine

[Zvika Meiseles <zvika.meiseles () gmail com>]

Hi,

I'm writing a program that uses packet capture via libpcap. It is built on
multiple platforms and OS's, and runs fine on most of them. However, the
combination of 32 bit binaries on a PPC64 Linux is failing (kernel
2.6.18-194.el5). 64 bit binaries of the same code work fine.

I've narrowed the problem down to the "memory mapped ring buffer" feature
(version 0.9.8 runs fine, >=1.0 fails).

At 1st, I saw that
   setsockopt(3, SOL_PACKET, PACKET_RX_RING, ...)
is failing with EBUSY, so I patched the code to call activate_mmap(...) BEFORE
calling iface_bind(...).

Now setsockopt(PACKET_RX_RING) works fine, but I still get the poll() busy-loop.

The symptoms are that no packet data is received by the client application, and
strace shows an endless list of
    poll([{fd=3, events=POLLIN}], 1, 1000)  = 1 ([{fd=3, revents=POLLIN}])

poll() says I have data to read, but it is ignored because the ring buffer
contains data with (status=TP_STATUS_KERNEL), whatever that means... :-)

In my testing, I've used the sniffex.c sample from the tcpdump site
(http://www.tcpdump.org/sniffex.c).

Any ideas as to why this is happening only in this configuration?

Thank you for your help in this matter,


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