On 16 February 2012 14:55, Jonathan Wakely wrote: > On 16 February 2012 12:55, HvW wrote: >> >> Hi, >> >> I have a library called Lib_Crc to compute the CRC of certain memory areas. >> This is used by another library called Lib_Appcfg which performs certain >> configuration checking and verification. >> >> My application "Test" needs to use both Lib_Crc functions and Lib_Appcfg >> function in order to perform its tasks. >> >> Why do I need to link both Lib_Crc and Lib_Appcfg in my application to use >> the Lib_Crc functions? Won't the symbols be available to the application >> form the Lib_AppCfg library? >> >> I have tried several linking options including -shared and -export-dynamic >> in multiple orders and arrangements, but in all cases when linking is done >> on the application, it complains that the Lib_Appcfg says that the Lib_Crc >> functions are "undefined references". To fix this I include Lib_Crc in my >> app. >> >> Any comments, suggestions or explanations will be appreciated. > > The answer depends what platform you're using which you didn't say, > and isn't really a GCC question, it's about the linker. You also > haven't shown your linker commands or the actual error messages you're > getting, which prevents anyone giving an accurate answer. > > For GNU/Linux if you link Lib_AppCfg to Lib_Crc it should have a > DT_NEEDED tag, which will cause the dynamic linker to load Lib_Crc > when starting the application. On some recent GNU/Linux systems you might also need to use --copy-dt-needed-entries when linking your application, to cause the linker to look in Lib_AppCfg's library dependencies for the unresolved symbols.
