tcpdump mailing list archives

Re: Capturing in 32 bit guests


From: Michael Richardson <mcr () sandelman ca>
Date: Wed, 01 Feb 2012 08:32:07 -0500


"Guy" == Guy Harris <guy () alum mit edu> writes:
    Guy> On Jan 31, 2012, at 11:31 PM, Graeme Sheppard wrote:

    >> I have a problem capturing in a 32 bit guest on a 64 bit
    >> VZ/OpenVZ host.  It worked in a 64 bit guest but I had to change
    >> to 32 (another story.)

    Guy> So the host on which you're capturing is running a 32-bit Linux
    Guy> kernel and a 32-bit version of tcpdump?

No, openvz is a container, not a virtualization.
So the kernel is 64-bit, the userland in a chroot/jail+++ is 32-bit.
The kernel would be doing 32-bit emulation of many calls, but I'll bet
things like the mmap() interface are 64-bit.  

Not using that interface (I'm actually not sure if we can turn it off if
the kernel says it exists..) might help.

It might also be the container-ized network interface code screwing it
up, but I'd expect it to fail for the 64-bit "guest" as well.

(talking about "guest" wrt openvz is probably a bad thing)

-- 
]       He who is tired of Weird Al is tired of life!           |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] mcr () sandelman ottawa on ca http://www.sandelman.ottawa.on.ca/ |device driver[
   Kyoto Plus: watch the video <http://www.youtube.com/watch?v=kzx1ycLXQSE>
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