> > I guess it will fail during loading, but only if the variable x is not > defined anywhere in the rest of the kernel globally. Is my assumption > correct? Yes. > > Now I understand why the module will build successfully. The > > static int x > > declaration is specific to that file(file1.c) and the > > extern int x > > declaration in the other file(file2.c) will look for an x defined > globally in the kernel at the time of loading. > > This means the solution is still incorrect because if x is defined in > the kernel, then the module will build but the references to x in > file2.c will be to the x defined in the kernel. > > And if x is not defined in the rest of the kernel, then the module will > fail to load. > > Can someone please explain this? > > > > > > > > > > > > > >>-Vishwas. > >> > >> > >> > >>Mike DeKoker wrote: > >> > >> > >>>Yes, you'll end up having a local symbol for the > >>>static declaration and an undefined exported symbol > >>>for the extern declaration. The local symbol is not > >>>exported by definition. The undefined exported symbol > >>>cannot be exported because there is no object (i.e. > >>>variable or function) to which it is bound. > >>> > >>>-Mike DeKoker > >>> > >>>--- "Sponsel Carsten (ext)" > >>><carsten.sponsel@erln.gepas.de> wrote: > >>> > >>> > >>>>But then I've two symbols when i view my module with > >>>>nm... > >>>> > >>>>-----Original Message----- > >>>>From: Mike DeKoker [mailto:mdekoker@yahoo.com] > >>>>Sent: Freitag, 13. Februar 2004 18:20 > >>>>To: Sponsel Carsten (ext) > >>>>Subject: Re: global Variable in multiple files > >>>> > >>>> > >>>>Just define your variable as a module-level static > >>>>and > >>>>define an external reference to it in the other > >>>>source > >>>>files. This works for functions also. > >>>> > >>>>e.g. > >>>> > >>>>/* File1.c */ > >>>>static int x; > >>>> > >>>>/* File2.c */ > >>>>extern int x; > >>>> > >>>>This assumes that File1.o and File2.o are being > >>>>relocatably linked into a single object file. (Since > >>>>you're coding for a module they should be.) > >>>> > >>>>-Mike DeKoker > >>>> > >>>>--- "Sponsel Carsten (ext)" > >>>><carsten.sponsel@erln.gepas.de> wrote: > >>>> > >>>> > >>>>>Hi friends, > >>>>> > >>>>>it might be a simple question: > >>>>> > >>>>>What's the best way to get (to define) a global > >>>>>variable which can be used in multiple files of a > >>>>>kernel module in Linux Kernel 2.6? The variable > >>>>>should not be exported as a symbol. In my special > >>>>>problem I need an array of a struct which is > >>>> > >>>>useable > >>>> > >>>> > >>>>>in all sourcefiles which form my kernel module. > >>>>> > >>>>>thanks, > >>>>>Carsten > >>>>> > >>>> > >>>>snip > >>>> > >>>>__________________________________ > >>>>Do you Yahoo!? > >>>>Yahoo! Finance: Get your refund fast by filing > >>>>online. > >>>>http://taxes.yahoo.com/filing.html > >>> > >>> > >>> > >>>__________________________________ > >>>Do you Yahoo!? > >>>Yahoo! Finance: Get your refund fast by filing online. > >>>http://taxes.yahoo.com/filing.html > >>> > >>>-- > >>>Kernelnewbies: Help each other learn about the Linux kernel. > >>>Archive: http://mail.nl.linux.org/kernelnewbies/ > >>>FAQ: http://kernelnewbies.org/faq/ > >>> > >> > >> > >> > > > > > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
