On Tue, Feb 24, 2009 at 02:05:25PM -0500, Fred Isaman wrote: > The pnfs tree base of of 2.6.29-rc5 uses the new find_last_bit > function (defined in > lib/find_last_bit.c) in a file in the fs/nfs directory. Myself and > another developer (though no one else so far) get the following error > during compile: > > Kernel: arch/x86/boot/bzImage is ready (#5) > Building modules, stage 2. > MODPOST 515 modules > ERROR: "find_last_bit" [fs/nfs/nfs.ko] undefined! > make[2]: *** [__modpost] Error 1 > make[1]: *** [modules] Error 2 > make: *** [sub-make] Error 2 > > > Note that find_last_bit() is not used in any file in the fs directory. > If I add it to any function that is EXPORT_SYMBOL'ed > from the fs directory, suddenly the compile errors go away. (See the > below patch for a more concrete example.) > > I am not sure what is going on, and why it only affects some > developers, but it looks a lot like the kbuild system > is deciding that the library does not need to be included at the fs > directory level, so isn't including it in fs/nfs where > it is needed. kbuild only links in libaries if there is any users of siad library. And your normal config has no users of lib/find_last_bit.c so it is not linked into the kernel. The general rule is that if any in tree module uses a library then the library is always linked in. And to always link in a library you need to patch the Makefile as Randy suggest in his mail. Sam -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
