Re: libpcap: 64bit machine has no compatible 32-bit libpcap library

[Guy Harris <guy () alum mit edu>]

On Mar 25, 2013, at 7:22 AM, Michael Richardson <mcr () sandelman ca> wrote:

> > > > > > "wen" == wen lui <esolvepolito () gmail com> writes:
>    wen> I want to compile a `.c` file to 32-bit executable using `gcc`
>    wen> option `-m32` with libpcap the machine is linux 64bit fedora 16
>
>    wen> how to solve this problem? thanks!
>
> install a 32-bit libpcap.
> I don't know how to do this on Fedora, but I'm sure it is possible.

This post:

        http://forums.fedoraforum.org/showpost.php?p=1486052&postcount=2

says

        I'm far a linux guru myself, but I'll tell you how stumbled onto installing the 32-bit libraries. Some other 
distros have an obvious option to add it, but Fedora doesn't make it obvious. 

        Go into the GUI add/remove software app and, in the options somwhere, uncheck the option to only show "native 
packages", which will then allow the .i686 32-bit packages to become visible from the repos. 

        Now, search for "libc" or "glibc" (I can't remember which I used) and choose the 32-bit, i686 library package. 
That should bring in most of the core/base stuff. You may need some more packages after that for whatever you're trying 
to do, but that will get you started.

The original question for that post was asked about Fedora 15, but experimenting with my Fedora 16 with KDE seems to 
indicate that it applies there as well.  In its add/remove software app (Apper), the instruction set architecture for a 
package ("i686" for 32-bit and "x86_64" for 64-bit; your mileage may vary if you're not using an x86 machine) only 
shows up, in a tooltip, when you hover the mouse pointer over an item.

I didn't try installing any of the 32-bit packages (you'd need both the "user" and "developer" packages), but I presume 
that installing 32-bit versions of all the "core/base stuff", along with 32-bit versions of libpcap and libpcap-devel, 
should do the job.

Note, by the way, that 32-bit libpcap will *NOT* work atop a 64-bit kernel if your kernel version is less than 2.6.27 
and greater than whatever version first included the memory-mapping support for PF_PACKET sockets - those kernel 
versions only have the TPACKET_V1 layout for the memory-mapped buffer, and that one is different in 32-bit and 64-bit 
kernels.  2.6.27 introduces TPACKET_V2, in which the layout is the same for 32-bit and 64-bit kernels, and 32-bit code 
dealing with memory-mapped PF_PACKET sockets works fine atop 32-bit or 64-bit kernels.
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