Re: [PATCH][RFC] Allow linking from custom staticlib.a instead of list of object files

[Christian Bell <csbell () myri com>]

On Jan 8, 2010, at 7:22 PM, Guy Harris wrote:

> On Jan 8, 2010, at 12:56 PM, Guy Harris wrote:
>
> > You might want to call it ARCHIVELIBS, by analogy to LIBS.
>
> Another possibility, if the routines are in an installed library,  
> would be to just add that library to LIBS.  The shared libpcap will  
> be linked with all the libraries in LIBS, so programs linked with  
> the shared libpcap will pick up the shared versions of those  
> libraries, and programs whose build procedures use the new-in-1.0.0  
> pcap-config script if it's available (top-of-tree tcpdump and  
> Wireshark both do; I'll check whether Wireshark 1.2.x does, and, if  
> not, look at backporting that) will, for a static build, link with  
> the library if you pass --static to pcap-config.
>
> Note that top-of-tree libpcap, on Linux systems that have libnl,  
> will use routines from it unless you explicitly use --without-libnl,  
> so it already requires additional libraries on at least some  
> platforms.

You're right.  To be quite honest, my main goal (as a vendor) is just  
to lower the barrier for users to link with a single library without  
worrying about extra dependencies (libs or search paths).  Other  
vendors seem to use the ADDLOBJS method and while I think this helps  
ease things, I'm just uncomfortable about burning in object files by  
name in an external project.

If tcpdump/wireshark use the pkg-config method, it isn't the case for  
all packages out there and when there's extra dependencies, both  
libpcap.a and .so can fail in some odd way (missing -l or broken  
rpath).  For example, just building findalldevstest requires  
LD_LIBRARY_PATH to be modified to run it out of the box if -Llib is  
not in a standard search path.  I guess it could use pcap-config, but  
pcap-config is currently only built by the install rule.

I think the pkg-config method is an honest attempt to make the problem  
easier to solve but it doesn't plug all the holes -- relocatable rpms  
can't easily rewrite the rpath in the pkg-config and the admins we've  
encountered like to install external packages in non-standard locations.

Nevertheless, I'll proceed with only modifying LIBS= and seeing what  
the fallout is.  If it turns out to be a hassle, we'll just modify how  
we build libpcap.so.

        . . christian

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