crt1.o: In function `_start': - undefined reference to `main' in Linux

linux main undefined-reference
Blackforest picture Blackforest · Jun 20, 2012 · Viewed 89k times · Source

I am porting an application from Solaris to Linux

The object files which are linked do not have a main() defined. But compilation and linking is done properly in Solaris and executable is generated. In Linux I get this error 

    /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'

My problem is, I cannot include new .c/.o files since its a huge application and has been running for years. How can I get rid of this error?

Code extractes of makefile:

RPCAPPN = api
LINK = cc 

    $(RPCAPPN)_server: $(RPCAPIOBJ)
            $(LINK) -g $(RPCAPIOBJ) -o $(RPCAPPN)_server $(IDALIBS) $(LIBS) $(ORALIBS) $(COMMONLIB) $(LIBAPI) $(CCLIB) $(THREADLIB) $(DBSERVERLIB) $(ENCLIB)

Answer

Paul R picture Paul R · Jun 20, 2012

Try adding -nostartfiles to your linker options, i.e.

$(LINK) -nostartfiles -g ...

From the gcc documentation:

-nostartfiles
    Do not use the standard system startup files when linking. The standard system libraries are used normally, unless -nostdlib or -nodefaultlibs is used.

This causes crt1.o not to be linked (it's normally linked by default) - normally only used when you implement your own _start code.

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