tcpdump mailing list archives

Re: [PATCH] enable memory mapped access to ethernet device for linux


From: "Gianluca Varenni" <gianluca.varenni () cacetech com>
Date: Wed, 5 Dec 2007 08:23:45 -0800

From what you said, you basically changed the behavior of the snaplen
parameter of pcap_open_live(). At the risk of being annoing, I find it a really bad idea. If it's called snaplen, it's the snaplen, period. Isn't it possible to add a pcap function to set such parameter (or eventually create a new pcap_open_live_mmap() function)?

Have a nice day
GV

----- Original Message ----- From: "Paolo Abeni" <paolo.abeni () telecomitalia it>
To: <tcpdump-workers () lists tcpdump org>
Cc: <simon () patarin info>; <cpw () lanl gov>
Sent: Wednesday, December 05, 2007 3:11 AM
Subject: [tcpdump-workers] [PATCH] enable memory mapped access to ethernet device for linux


hi list,

Following the discussion about the memory mapped access for Linux, I
tried to rework some existing code (originally independently created by
Simon Patarin and Phil Wood) to enable this functionality with the
minimum impact on the current pcap code.

It does not use environment variables to control the memory mapped ring
parameters; instead the requested snap len is used: the low order bytes
are used to select the ring frame size and the high order bytes are used
to select the ring frame number. If the high order bytes is 0, like in
every current libpcap usage, a reasonable default is used.

The poll function is used to implement the timeout in the read method:
must I add some autoconf check for poll() availability ?!? or use
select() instead ?!?

I really appreciated any comments and or review on this matter (even a
'please don't try to push this thing ...' :-)

Thanks,

Paolo
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